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draft-bidulock-sigtran-tua-00

Description: Request For Comments

You can download source copies of the file as follows:

draft-bidulock-sigtran-tua-00.txt in text format.
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Listed below is the contents of file draft-bidulock-sigtran-tua-00.txt.




Network Working Group                                     Brian Bidulock
INTERNET-DRAFT                                       OpenSS7 Corporation

Expires in six months                                   January 10, 2002

                     SS7 TCAP-User Adaptation Layer
                                  TUA
                  <draft-bidulock-sigtran-tua-00.txt>

Status of this Memo

  This document is an Internet-Draft and is in full conformance with all
  provisions of Section 10 or RFC 2026.  Internet-Drafts are working
  documents of the Internet Engineering Task Force (IETF), its areas,
  and its working groups.  Note that other groups may also distribute
  working documents as Internet-Drafts.

  Internet-Drafts are draft documents valid for a maximum of six months
  and may be updated, replaced, or obsoleted by other documents at any
  time.  It is inappropriate to use Internet-Drafts as reference
  material or to cite them other than as 'work in progress'.

  The list of current Internet-Drafts can be accessed at
  http://www.ietf.org/ietf/1id-abstracts.txt

  The list of Internet-Draft Shadow Directories can be accessed at
  http://www.ietf.org/shadow.html

  To learn the current status of any Internet-Draft, please check the
  '1id-abstracts.txt' listing contained in the Internet-Drafts Shadow
  Directories on ftp.is.co.za (Africa), nic.nordu.net (Europe),
  munnari.oz.au (Pacific Rim), ftp.ietf.org (US East Coast), or
  ftp.isi.edu (US West Coast).

Abstract

  This document defines a protocol for the transport of any SS7 TCAP-
  User signalling (e.g, INAP, MAP, etc.) over IP using the Stream
  Control Transport Protocol [RFC 2960].  The protocol should be modular
  and symmetric, to allow it to work in diverse architectures, such as a
  Signalling Gateway and IP Signalling End-point architecture.  Protocol
  elements are added to allow seamless operation between peers in the
  SS7 and IP domains.

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1.  Introduction

  This draft defines a protocol for the transport of SS7 TCAP [Q.771,
  T1.114] Users (i.e, MAP, INAP, etc.) signalling messages over IP using
  the Stream Control Transmission Protocol (SCTP) [RFC 2960].  This
  protocol would be used between a Signalling Gateway (SG) and
  Signalling End-point located in an IP network.  Additionally, the
  protocol can be used to transport SS7 TCAP users between two
  signalling end-points located within an IP network.

1.1.  Scope

  There is on-going integration of SCN networks and IP networks.
  Network service providers are designing all IP architectures that
  include support for SS7 signalling protocols.  IP provides an
  effective way to transport user data and for operators to expand their
  networks and build new services.  In these networks, there is a need
  for interworking between the SS7 and IP domains [RFC 2719].

  This document details the delivery of TC-user messages (MAP, CAP,
  INAP, etc.) over IP between two signalling end-points.  Consideration
  is given for the transport from an SS7 Signalling Gateway (SG) to an
  IP signalling node (such as an IP-resident Database) as described in
  the Framework Architecture for Signalling Transport [RFC 2719] This
  protocol can also support transport of TC-user messages between two
  end-points wholly contained within and IP network.

  The delivery mechanism addresses the following criteria:

   o Support for transfer of TCAP messages (INAP, MAP, etc.)
   o Support for TCAP operation class 1, 2, 3 and 4 operation.
   o Support for the seamless operation of TC-User protocol peers.
   o Support for the management of SCTP transport associations between
     an SG and one ore more IP-based signalling nodes.
   o Support for distributed IP-based signalling nodes.
   o Support for the asynchronous reporting of status changes to
     management.

1.2.  Terminology

  Application Server (AS) - a logical entity serving a specific Routing
     Key.  An example of an Application Server is a virtual database
     element handling all HLR or SCP transactions for a particular SS7
     Signalling Point.  The AS contains a set of one or more unique
     Application Server Processes, of which one or more is normally
     actively processing traffic.  There is a 1:1 relationship between
     an Application Server and a Routing Key.

  Application Server Process (ASP) - a process instance of an
     Application Server.  An Application Server Process serves as an
     active, backup, load-share or broadcast process of an Application
     Server (e.g, part of a distributed signalling node or database
     element).  Examples of ASPs are MGCs, IP SCPs, or IP HLRs.  An ASP
     contains an SCTP end-point and may be configured to process traffic

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     within more that one Application Server.

  Association - refers to an SCTP association [RFC 2960].  The
     association provides the transport for the delivery of TCAP
     protocol data units and TUA layer peer messages.

  Component Sub-layer (TC)
     The Component Sub-layer of TCAP [Q.771].

  Fail-over - the capability to reroute signalling traffic as required
     to an alternate Application Server Process, or group of ASPs,
     within an Application Server in the event of failure or
     unavailability of a currently used Application Server Process.
     Fail-over may apply upon the return to service of a previously
     unavailable Application Server Process.

  Host - the computing platform that the process (SGP, ASP or IPSP) is
     running on.

  IP Server Process (IPSP) - a process instance of an IP-based
     application.  An IPSP is essentially the same as an ASP, except
     that it uses TUA in a point-to-point fashion.

  Layer Management (LM) - a nodal function that handles the inputs and
     outputs between the TUA layer and a local management entity.

  Message Transfer Part (MTP)
     The Message Transfer Part [Q.701, T1.111] of the SS7 protocol.

  Nodal Interworking Function (NIF) - an implementation dependent
     interworking function present at a Signalling Gateway that
     interworks primitives and procedures between the TCAP and TUA
     layers in the SG.

  Network Appearance (NA) - a value that identifies the SS7 network
     context of a Routing Key.  The Network Appearance value is of
     significance only within an administrative domain; it is
     coordinated between the SG and ASP.

  Network Byte Order - the ordering of bytes most-significant-byte
     first, also referred to as Big Endian.

  Routing Context (RC) - a value that uniquely identifies a Routing Key
     and an Application Server.  Routing Context values are either
     configured using a configuration management interface, or by using
     the Routing Key Management (RKM) messages and procedures defined
     for TUA.

  Routing Key (RK) - describes a set of SS7 parameters and parameter
     values that uniquely define the range of signalling traffic to be
     handled by a particular Application Server.

  Signalling Connection Control Part (SCCP) - The Signalling Connection
     Control Part [Q.711] of the SS7 protocol.

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  Signalling Gateway (SG) - a signalling agent that exchanges SCN native
     signalling at the edge of the IP network [RFC 2719].  An SG appears
     to the SS7 network as an SS7 Signalling Point.  An SG contains a
     set of one or more Signalling Gateway Processes, of which one or
     more is normally actively processing traffic.  When an SG contains
     more than one SGP, the SG is a logical entity and the contained
     SGPs are assumed to be coordinated into a single management view
     both toward the SS7 network and toward the supported Application
     Servers.

  Signalling Gateway Process (SGP) - a process instance of a Signalling
     Gateway.  It serves as an active, backup, load-sharing or broadcast
     process of a Signalling Gateway.

  Stream - an SCTP stream; a unidirectional logical channel established
     from one SCTP endpoint to another associated SCTP endpoint, within
     which all user messages are delivered in sequence, except for those
     submitted to the unordered delivery service.

  Transaction Capabilities Application Part (TCAP) - The Transaction
     Capabilities Application Part [Q.771, T1.114] of the SS7 protocol.

  Transaction Mapping Function (TMF) - an implementation dependent
     function that is responsible for resolving the address and
     application context presented in the incoming TUA message to the
     correct SCTP association and Routing Context for the desired
     application.  The TMF MAY use routing context or routing key
     information as selection criteria for the appropriate SCTP
     association.

  Transaction Sublayer (TR) - The Transaction Sublayer of TCAP [Q.771].

  Transport Address - an address that serves as a source or destination
     for the unreliable packet transport service used by SCTP.  In IP
     networks, a transport address is defined by the combination of IP
     address and an SCTP port number [1].

1.3.  TUA Overview

1.3.1.  Signalling Transport Architecture

  The framework architecture that has been defined for SCN signalling
  transport over IP [RFC 2719] uses multiple components, including an IP
  transport protocol, a signalling common transport protocol and an
  adaptation module to support the services expected by a particular SCN
  signalling protocol from its underlying protocol layer.

  In general terms, the TUA architecture can be modeled as a peer-to-
  peer architecture.  The first section considers the SS7-to-IP
  interworking architectures for TCAP class 1, 2, 3, and 4 operations.
  For this case, it is assumed that the ASP initiates the establishment
  of the SCTP association with the SG.

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1.3.2.  Protocol Architecture for Classes 1, 2, 3 and 4

  In this architecture (illustrated in Figure 1), the TCAP and TUA
  layers interface in the SG.  A Nodal Interworking Function (NIF)
  provides for interworking between the TCAP and TUA layers and provides
  for the transfer of the user messages as well as management messages.

          .........         ...............        .........
          :       :         :             :        :       :
          :  SEP  :   SS7   :             :   IP   :       :
          :   or  :.........:     SG      :........:  ASP  :
          :  STP  :         :             :        :       :
          :.......:         :.............:        :.......:
           _______           _____________          _______
          |       |         |             |        |       |
          | TC-U  |         |     NIF     |        | TC_U  |
          |-------|         |------ ------|        |-------|
          | TCAP  |         | TCAP |      |        |       |
          |-------|         |------| TUA  |        |  TUA  |
          | SCCP  |         | SCCP |      |        |       |
          |-------|         |------|------|        |-------|
          | MTP3  |         | MTP3 |      |        |       |
          |-------|         |------| SCTP |        | SCTP  |
          | MTP2  |         | MTP2 |      |        |       |
          |-------|         |------|------|        |-------|
          |  L1   |         |  L1  |  IP  |        |  IP   |
          |_______|         |______|______|        |_______|
              |                |       |               |
              |________________|       |_______________|

                 TC-U - TCAP-User (e.g. - MAP/INAP)
                 STP  - SS7 Signaling Transfer Point
                 NIF  - Nodal Interworking Function

                      Figure 1.  Protocol Architecture

1.3.3.  All IP Architecture

  This architecture, illustrated in Figure 2, can be used to carry a
  protocol which uses the transport services of TCAP, but is contained
  within an IP network.  This allows extra flexibility in developing
  networks, especially when interaction between legacy signalling is not
  needed.  The architecture removes the need for a signalling gateway
  function.

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                     ........        ........
                     :      :   IP   :      :
                     :  AS  :........:  AS  :
                     :      :        :      :
                     :......:        :......:
                      ______          ______
                     |      |        |      |
                     |  AP  |        |  AP  |
                     |------|        |------|
                     | TUA  |        | TUA  |
                     |------|        |------|
                     | SCTP |        | SCTP |
                     |------|        |------|
                     |  IP  |        |  IP  |
                     |______|        |______|
                        |                |
                        |________________|

             AP - Application Protocol (e.g. - MAP/INAP)

                       Figure 2.  All IP Architecture

1.3.4.  ASP Fail-over Model and Terminology

  The TUA protocol supports ASP fail-over functions to support a high
  availability of transaction processing capability.

  An Application Server can be considered as a list of all ASPs
  configured or registered to handled TC-user messages within a certain
  range of routing information, or within a certain set of transaction
  dialogues, known as a `Routing Key.'  One or more ASPs in the list may
  normally be active to handle traffic, while others may be inactive but
  available in the event of failure or unavailability of the active
  ASPs.

  For operational considerations, see Appendix A.

1.3.5.  Services Provided by the TUA Layer

1.3.5.1.  Support for the transport of TCAP-User Messages

  The TUA supports the transfer of TC-user messages.  The TUA layer at
  the SG and the ASP support the seamless transport of user messages
  between the SG and the ASP.

1.3.5.1.1.  TCAP Operation Class Support

  Depending on the TC-users supported, the TUA shall support the 4
  possible TCAP operation classes transparently.  The TCAP operation
  classes are defined as follows:

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  Operation Class 1 - provides for transactions reporting both
                      success and failure.
  Operation Class 2 - provides for transactions reporting failure.
  Operation Class 3 - provides for transactions reporting success.
  Operation Class 4 - provides for transactions reporting neither
                      success nor failure.

1.3.5.2.  Native Management Functions

  The TUA layer provides the capability to indicate errors associated
  with the TUA-protocol messages and to provide notification to local
  management and the remote peer as necessary.

1.3.5.3.  Interworking with TCAP Management Functions

  The TUA layer provides interworking with TCAP management functions at
  the SG for seamless interoperation between the SCN network and the IP
  network.  TUA provides the following management functions:

   (1)   Provides an indication to the TC-user at an ASP that an SS7
         subsystem, SCCP User Part or MTP Destination is unavailable.

   (2)   Provides an indication to the TC-user at an ASP that an SS7
         subsystem, SCCP User Part or MTP Destination is available.

   (3)   Provides an indication to the TC-user at an ASP that an SS7
         subsystem or MTP Destination is congested (flow controlled).

   (4)   Provides the initiation of an audit of SS7 subsystems or MTP
         Destinations status at the SG.

  The interworking with TCAP management messages consists of DUNA, DAVA,
  DAUD, DRST, DUPU or SCON messages on receipt of management events to
  the appropriate ASPs.  The primitives in Table 1 are sent between the
  TCAP and TUA management functions in the SG to trigger events in the
  IP and SS7 domain.

  The TUA layer provides transparent passing of SCCP availability,
  unavailability and congestion status indication primitives (N-STATE,
  N-PCSTATE and N-COORD) as provided for in ITU-T Q.771 2.2.3 [Q.771].

1.3.5.4.  Support for the Management of SCTP Associations

  The TUA layer at the SGP maintains the availability state of all
  configured remote ASPs, to manage the SCTP Associations and the
  traffic between TUA peers.  As well, the active/inactive and
  congestion state of remote ASPs is maintained.

  The TUA layer MAY be instructed by local management to establish an
  SCTP association to a peer TUA node.  This can be achieved using the
  M-SCTP_ESTABLISH primitives to request, indicate and confirm the
  establishment of an SCTP association with a peer TUA node.  To avoid

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               Table 1. Mapping of Management Primitives

   +------------------------+---------------------------+------------+
   |         Name           |         Reference         |    TUA     |
   +-----------+------------+-------------+-------------+ Management |
   | Generic   | Specific   | ITU-T Q.711 | ANSI T1.112 |  Message   |
   +-----------+------------+-------------+-------------+------------+
   | N-STATE   | Request    |  6.3.2.3.2  |  2.3.2.3.2  |    DUNA    |
   |           | Indication |             |             |    DAVA    |
   |           |            |             |             |    SCON    |
   +-----------+------------+-------------+-------------+------------+
   | N-PCSTATE | Indication |  6.3.2.3.3  |  2.3.2.3.4  |    DUNA    |
   |           |            |             |             |    DAVA    |
   |           |            |             |             |    SCON    |
   |           |            |             |             |    DUPU    |
   +-----------+------------+-------------+-------------+------------+
   | N-COORD   | Request    |  6.3.2.3.1  |  2.3.2.3.3  |    DRST    |
   |           | Indication |             |             |            |
   |           | Response   |             |             |            |
   |           | Confirm    |             |             |            |
   +-----------+------------+-------------+-------------+------------+

  redundant SCTP associations between two TUA peers, one side (client)
  SHOULD be designated to establish the SCTP association, or TUA
  configuration information maintained to detect redundant associations
  (e.g, via knowledge of the expected local and remote SCTP endpoint
  addresses).

  Local management MAY request from the TUA layer the status of the
  underlying SCTP associations using the M-SCTP_STATUS request and
  confirm primitives.  Also, the TUA MAY autonomously inform local
  management of the reason for the release of an SCTP association,
  determined either locally within the TUA layer or by a primitive from
  the SCTP.

  Also, the TUA layer MAY inform the local management of the change in
  status of an ASP or AS.  This MAY be achieved using the M-ASP_STATUS
  request or M-AS_STATUS request primitives.

1.4.  Functional Areas

1.4.1.  Dialogue Identifiers, Routing Contexts and Routing Keys

1.4.1.1.  Overview

  The mapping of TCAP messages into dialogues between the SGP and the
  Application Servers is determined by Dialogue Identifiers, Routing
  Keys and their associated Routing Contexts.

  A Routing Key is essentially a set of TCAP parameters used to direct
  TCAP messages; whereas, the Routing Context parameter is a 4-byte
  value (unsigned integer) that is associated to that Routing Key in a
  1:1 relationship.  The Routing Context therefore can be viewed as an

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  index into a sending node's Transaction Mapping Function tables
  containing the Routing Key entries.

  Possible TCAP address/routing information that comprise a Routing Key
  entry includes, for example, a local and remote Point Code, Subsystem
  Number, Global Title Address, Application Context, local and remote
  Transaction Id pairs, or TC-User specific information such as User
  Information, IMSI, SLP.  The particular information used to define a
  TUA Routing Key is application and network dependent, and none of the
  above examples are requirements for TUA.

  An Application Server Process (ASP) may be configured to process
  signalling traffic related to more than one Application Server (AS),
  over a single SCTP Association.  ASP Active (ASPAC) and ASP Inactive
  (ASPIA) management messages (see Section 3) use the Routing Context to
  discriminate signalling traffic to be started or stopped.  At an ASP,
  the Routing Context parameter uniquely identifies the range of
  signalling traffic associated with each Application Server that the
  ASP is configured to receive.

1.4.1.2.  Routing Key Limitations

  Routing Keys SHOULD be unique in the sense that each received TCAP
  message SHOULD have a full or partial match to a single routing
  result.  It is not necessary for the parameter range values within a
  particular Routing Key to be continuous.  For example, an AS could be
  configured to support transaction processing for multiple ranges of
  subscribers that are not represented by contiguous Global Title
  Addresses.

1.4.1.3.  Managing Routing Context and Routing Keys

  There are two ways to provision a Routing Key at an SGP.  A Routing
  Key may be configured statically using an implementation dependent
  management interface, or dynamically managed using the the TUA Routing
  Key registration procedures.

  When using a management interface to configure Routing Keys, the
  Transaction Mapping Function within the SGP is not limited to the set
  of parameters defined in this document.  Other implementation
  dependent distribution algorithms may be used.

1.4.1.4.  Transaction Mapping Function

  To perform its addressing and relaying capabilities, the TUA makes use
  of an Transaction Mapping Function (TMF).  This function is considered
  part of TUA, but the way it is realized is left implementation or
  deployment dependent (local tables, SCCP GTT database, DNS [RFC 2916],
  LDAP, etc.)

  The TMF is invoked when a message is received at the incoming
  interface.  The TMF is responsible for resolving the application
  context, address and transaction ids presented in the incoming TCAP
  message to SCTP associations and destinations within the IP network.

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  The TMF will select the key information available.  The Routing Keys
  reference an Application Server, which will normally have one or more
  ASPs processing transactions for the AS.  The availability and status
  of the ASPs is handled by TUA ASP management messages.

  Possible SS7 application context, address or routing information that
  comprise a Routing Key entry includes, for example, SCCP subsystem
  number and SCCP addresses and Global Title addresses, Transaction ID,
  and Application Context.

  It is expected that the routing keys will be provisioned via a MIB,
  dynamic registration or an external process, such as a database.

1.4.1.4.1.  Transaction Mapping at the SG

  To direct messages received from the SS7 network to the appropriate IP
  destination, the SGP must perform a transaction mapping function using
  information from the received TCAP message.

  To support this transaction mapping, the SGP might, for example,
  maintain the equivalent of a network address translation table,
  mapping incoming TCAP message information to an Application Server for
  a particular application and set of transactions.  This could be
  accomplished by comparing the addressing, dialog or component portions
  of the incoming TCAP message to currently defined Routing Keys in the
  SGP.  These Routing Keys could in turn map directly to an Application
  Server that is enabled by one or more ASPs.  These ASPs proxy dynamic
  status information regarding their availability, transaction handling
  capabilities and congestion to the SGP using various management
  messages defined in the TUA protocol.

  The list of ASPs in the AS is assumed to be dynamic, taking into
  account the availability, transaction handling capability and
  congestion status of the individual ASPs in the list, as well as
  configuration changes and possible fail-over mechanisms.

  Normally, one or more ASPs are active in the AS (i.e, currently
  processing transactions) but in certain failure and transition cases
  it is possible that there may not be an active ASP available.  The SGP
  will buffer the message destined for this AS for a time T(r) or until
  an ASP becomes available.  When no ASP becomes available before expiry
  of T(r), the SGP will flush the buffered messages and initiate the
  appropriate TCAP abort procedures.

  If there is no match for an incoming message, a default treatment MAY
  be specified.  Possible solutions are to provide a default Application
  Server to direct all unallocated transactions to a (set of) default
  ASP(s), or to drop the messages and provide a notification to
  management.  The treatment of unallocated transactions is
  implementation dependent.

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1.4.1.4.2.  Transaction Mapping at the ASP

  To direct messages to the SS7 network, the ASP MAY perform a
  transaction mapping to choose the proper SGP for the given message.
  This is accomplished by observing the Application Context, Destination
  Address, Destination Transaction Id, and other elements of the
  outgoing message, SS7 network status, SGP availability, and Routing
  Context configuration tables.

  A Signalling Gateway may be composed of one or more SGPs [2].  There
  is, however, no TUA messaging to manage the status of an SGP.
  Whenever an SCTP association to an SGP exists, it is assumed to be
  available.  Also, every SGP of one SG communicating with one ASP
  regarding one AS provides identical SS7 connectivity to this ASP.

  In general, an ASP routes responses to the SGP that it received
  messages from; within the routing context which it is currently active
  and receiving transactions.  The routing context itself is used by the
  ASP to select the SGP.

1.4.1.5.  Signalling Gateway SS7 Layers

  The SG is responsible for terminating up to the TC-user of the SS7
  protocol, and offering an IP-based extension to its users.

  From an SS7 perspective, it is expected that the Signalling Gateway
  transmits and receives TCAP messages to and from the SS7 Network over
  standard SS7 network interfaces, using the services of the SCCP
  [Q.711] and MTP [Q.704] to provide transport of the messages.

  Note that it is also possible for the SCCP services to be provided
  using the services of the SCCP-User Adaptation Layer (SUA) [SUA] and
  the MTP3-User Adaptation Layer (M3UA) [M3UA].

  The TC-SAP through which TUA at the SG obtains its services could
  reside at a Signalling Transfer Point (STP) or Signalling End Point
  (SEP) [Q.705].

1.4.1.6.  SS7 and TUA Interworking at the SG

  The SGP provides a functional interworking of transport functions
  between the SS7 network and the IP network by also supporting the TUA
  adaptation layer.  It allows the TCAP application to exchange
  components in dialogues with an IP-based Application Server Process
  where the peer TC-User protocol layer exists.

  To perform TCAP management, it is required that the TC-User protocols
  at ASPs receive indications of subsystem availability and congestion,
  as well as user part availability and signalling point availability
  and congestion as they would be expected by an SS7 TCAP application.
  To accomplish this, the N-PCSTATE, N-STATE and N-COORD primitives
  received at the TCAP upper layer interface at the SG need to be
  propagated to the remote TC-user lower layer interface at the ASP.

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  SCCP management messages (such as SSP, SSA) and MTP management
  messages (such as TFP, TFA) received from the SS7 network MUST NOT be
  encapsulated.  The SG MUST terminate these messages and generate TUA
  message as appropriate.

1.4.1.7.  Application Server

  A cluster of Application Servers is responsible for providing the
  overall support for one ore more SS7 upper layers.  From an TCAP
  standpoint, an Application Part provides complete support for the
  upper layer service within a given Application Context.  As an
  example, an Application Part providing HLR capabilities could provide
  complete support for GSM MAP HLR (and any other, MSC or VLR
  application parts located at the signalling point) for a given point
  code.

  Where an ASP is connected to more than one SG, the TUA layer must
  maintain the status of configured SS7 destinations and route messages
  according to the availability/congestion status of potentially
  replicated subsystem.

1.4.1.8.  SCTP Stream Mapping

  The TUA supports SCTP streams.  The SG and AS need to maintain a list
  of SCTP and TC-Users for mapping purposes.  TC-Users requiring
  sequenced message transfer need to be sent over a stream using
  sequenced delivery.

  TUA SHOULD NOT use stream 0 for TUA management messages.  It is
  OPTIONAL that sequence delivery be used to preserve the order of
  management message delivery.

  All TUA Dialogue Handling (DH) messages not using the optional
  component handling interface (i.e, DH messages with components
  included) MAY select unordered delivery, depending on the requirements
  of the TC-User [3].  All TUA Component Handling (CH) messages and
  Dialogue Handling (DH) messages with external components SHOULD select
  ordered delivery.

  The stream selected is based upon the Sequence Control field in the
  Quality of Service parameter, the Dialogue Id given by the TC-User
  over the primitive interface and other traffic information available
  to the SGP or ASP.

1.4.2.  Redundancy Models

1.4.2.1.  Application Server Redundancy

  All TQRY and SSNM messages (e.g, TC-BEGIN, N-STATE) which match a
  provisioned Routing Key at an SGP are mapped to an Application Server.

  The Application Server is the set of all ASPs associated with a
  specific Routing Key.  Each ASP in this set may be active, inactive or
  unavailable.  Active ASPs handle traffic; inactive ASPs might be used

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  when active ASPs become unavailable.

  The fail-over model supports an "n+k" redundancy model, where "n" ASPs
  is the minimum number of redundant ASPs required to handle traffic and
  "k" ASPs are available to take over for a failed or available ASP.  A
  "1+1" active/backup redundancy is a subset of this model.  A simplex
  "1+0" model is also supported as a subset, with no ASP redundancy.

1.4.3.  Flow Control

  Local Management at an ASP may wish to stop traffic across an SCTP
  association to temporarily remove the association from service or to
  perform testing and maintenance activity.  The function could
  optionally be used to control the start of traffic onto a newly
  available SCTP association.

1.4.4.   Congestion Management

  The TUA layer is informed of local and IP network congestion by means
  of an implementation-dependent function (e.g, an implementation-
  dependent indication from the SCTP of IP network congestion).

  At an ASP or IPSP, the TUA layer indicates congestion to local TC-
  users by means of an appropriate TCAP primitive (N-PCSTATE, N-STATE,
  TC-NOTICE), as per current TCAP procedures, to invoke appropriate
  upper layer responses.  When an SG determines that the transport of
  SS7 messages is encountering congestion, the SG might trigger SS7
  Congestion messages to originating SS7 nodes, per the congestion
  procedures of the relevant SCCP [Q.711, T1.112] or MTP [Q.704, T1.111]
  standard.  (The triggering of SS7 Management messages from an SG is an
  implementation-dependent function.)

1.5.  Definition of TUA Boundaries

  TUA has three protocol boundaries: an upper boundary between TUA and
  the TC-User; a lower boundary between TUA and SCTP; and a layer
  management boundary between TUA and the Layer Management Function.

                       ...........
                       : TC-User :
                       :.........:  Layer
             Upper Boundary :       Management
                        ____:____   Boundary   ............
                       |   TUA   |.............:    LM    :
                       |_________|             :..........:
             Lower Boundary :
                       .....:.....
                       :   SCTP  :
                       :.........:

                    Figure 3.  TUA Protocol Boundaries

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1.5.1.  Definition of Upper Boundary

  The primitives and messages listed in Table 2 are provided between the
  TUA and TC-User in support of Dialogue Handling [Q.771, T1.114].

            Table 2. Mapping of Dialogue Handling Primitives

   +--------------+------------+-------------+----------------+------+
   |Generic       | Specific   | ITU-T Q.771 |  ANSI T1.114   | TUA  |
   |Name          | Name       |  Reference  |    Message     | Msg  |
   +--------------+------------+-------------+----------------+------+
   |TC-UNI        | Request    | 3.1.2.2.1   | Unidirectional | TUNI |
   |              | Indication |             |                |      |
   +--------------+------------+-------------+----------------+------+
   |TC-BEGIN      | Request    | 3.1.2.2.2.1 | Query w/ Perm  |      |
   |              | Indication |             |                | TQRY |
   +--------------+------------+-------------+----------------+      |
   |------------- | ---------- | ----------- | Query w/o Perm |      |
   +--------------+------------+-------------+----------------+------+
   |TC-CONTINUE   | Request    | 3.1.2.2.2.2 |                |      |
   |(Initial)     | Indication |             |                |      |
   +--------------+------------+-------------+ Conv w/ Perm   |      |
   |TC-CONTINUE   | Request    | 3.1.2.2.2.3 |                | TCNV |
   |(Non-initial) | Indication |             |                |      |
   +--------------+------------+-------------+----------------+      |
   |------------- | ---------- | ----------- | Conv w/o Perm  |      |
   +--------------+------------+-------------+----------------+------+
   |TC-END        | Request    |             | Response       | TRSP |
   |              | Indication |             |                |      |
   +--------------+------------+ 3.1.2.2.2.4 +----------------+------+
   |TC-U-ABORT    | Request    |             | U-Abort        | TUAB |
   |              | Indication |             |                |      |
   +--------------+------------+-------------+----------------+------+
   |TC-P-ABORT    | Indication | 3.1.4.2     | P-Abort        | TPAB |
   +--------------+------------+-------------+----------------+------+
   |TC-NOTICE     | Indication | 3.1.2.2.3   | -------------- | TNOT |
   +--------------+------------+-------------+----------------+------+

  The primitives and messages listed in Table 3 are provided between the
  TUA and TC-User in OPTIONAL support of Component Handling [Q.771,
  T1.114].

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            Table 3. Mapping of Component Handling Primitives

     +-------------+------------+-------------+---------------+------+
     |Generic      | Specific   | ITU-T Q.771 |  ANSI T1.114  | TUA  |
     |Name         | Name       |  Reference  |    Message    | Msg  |
     +-------------+------------+-------------+---------------+------+
     |TC-INVOKE    | Request    | 3.1.3.2     | Invoke L      |      |
     |             | Indication |             |               | CINV |
     +-------------+------------+-------------+---------------+      |
     |------------ | ---------- | ----------- | Invoke NL     |      |
     +-------------+------------+-------------+---------------+------+
     |TC-RESULT-L  | Request    | 3.1.3.3     | Ret Result L  | CRES |
     |TC-RESULT-NL | Indication |             | Ret Result NL |      |
     +-------------+------------+-------------+---------------+------+
     |TC-U-ERROR   | Request    | 3.1.3.4     | Ret Error     | CERR |
     |             | Indication |             |               |      |
     +-------------+------------+-------------+---------------+------+
     |TC-U-REJECT  | Request    | 3.1.3.5     |               |      |
     |             | Indication |             |               |      |
     +-------------+------------+-------------+               |      |
     |TC-L-REJECT  | Request    |             | Reject        | CREJ |
     |             | Indication |             |               |      |
     +-------------+------------+ 3.1.4.1     |               |      |
     |TC-R-REJECT  | Request    |             |               |      |
     |             | Indication |             |               |      |
     +-------------+------------+-------------+---------------+------+
     |TC-U-CANCEL  | Request    | 3.1.3.6     |               | CCAN |
     |TC-L-CANCEL  | Indication |             | ------------- |      |
     +-------------+------------+-------------+---------------+------+

1.5.2.  Definition of Boundary between TUA and Layer Management

  M-SCTP_ESTABLISH request
  Direction: LM->TUA
  Purpose:   LM request ASP to establish an SCTP association with its
             peer.

  M-SCTP_ESTABLISH confirm
  Direction: TUA -> LM
  Purpose:   ASP confirms to LM that it has established an SCTP
             association with its peer.

  M-SCTP_ESTABLISH indication
  Direction: TUA -> LM
  Purpose:   TUA informs LM that a remote ASP has established an SCTP
             association.

  M-SCTP_RELEASE request
  Direction: LM -> TUA

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  Purpose:   LM requests ASP to release an SCTP association with its
             peer.

  M-SCTP_RELEASE confirm
  Direction: TUA -> LM
  Purpose:   ASP confirms to LM that it has released SCTP association
             with its peer.

  M-SCTP_RELEASE indication
  Direction: TUA -> LM
  Purpose:   TUA informs LM that a remote ASP has released an SCTP
             Association or the SCTP association has failed.

  M-SCTP RESTART indication
  Direction: TUA -> LM
  Purpose:   TUA informs LM that an SCTP restart indication has been
             received.

  M-SCTP_STATUS request
  Direction: LM -> TUA
  Purpose:   LM requests TUA to report the status of an SCTP
             association.

  M-SCTP_STATUS confirm
  Direction: TUA -> LM
  Purpose:   TUA responds with the status of an SCTP association.

  M-SCTP_STATUS indication
  Direction: TUA -> LM
  Purpose:   TUA reports the status of an SCTP association.

  M-ASP_STATUS request
  Direction: LM -> TUA
  Purpose:   LM requests TUA to report the status of a local or remote
             ASP.

  M-ASP_STATUS confirm
  Direction: TUA -> LM
  Purpose:   TUA reports status of local or remote ASP.

  M-AS_STATUS request
  Direction: LM -> TUA
  Purpose:   LM requests TUA to report the status of an AS.

  M-AS_STATUS confirm
  Direction: TUA -> LM
  Purpose:   TUA reports the status of an AS.

  M-NOTIFY indication
  Direction: TUA -> LM
  Purpose:   TUA reports that it has received a Notify message from
             its peer.

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  M-ERROR indication
  Direction: TUA -> LM
  Purpose:   TUA reports that it has received an Error message from
             its peer or that a local operation has been unsuccessful.

  M-ASP_UP request
  Direction: LM -> TUA
  Purpose:   LM requests ASP to start its operation and send an ASP Up
             message to its peer.

  M-ASP_UP confirm
  Direction: TUA -> LM
  Purpose:   ASP reports that is has received an ASP UP Ack message
             from its peer.

  M-ASP_UP indication
  Direction: TUA -> LM
  Purpose:   TUA reports it has successfully processed an incoming ASP
             Up message from its peer.

  M-ASP_DOWN request
  Direction: LM -> TUA
  Purpose:   LM requests ASP to stop its operation and send an ASP
             Down message to its peer.

  M-ASP_DOWN confirm
  Direction: TUA -> LM
  Purpose:   ASP reports that is has received an ASP Down Ack message
             from its peer.

  M-ASP_DOWN indication
  Direction: TUA -> LM
  Purpose:   TUA reports it has successfully processed an incoming ASP
             Down message from its peer, or the SCTP association has
             been lost or reset.

  M-ASP_ACTIVE request
  Direction: LM -> TUA
  Purpose:   LM requests ASP to send an ASP Active message to its
             peer.

  M-ASP_ACTIVE confirm
  Direction: TUA -> LM
  Purpose:   ASP reports that is has received an ASP Active Ack
             message from its peer.

  M-ASP_ACTIVE indication
  Direction: TUA -> LM
  Purpose:   TUA reports it has successfully processed an incoming ASP
             Active message from its peer.

  M-ASP_INACTIVE request
  Direction: LM -> TUA

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  Purpose:   LM requests ASP to send an ASP Inactive message to its
             peer.

  M-ASP_INACTIVE confirm
  Direction: LM -> TUA
  Purpose:   ASP reports that is has received an ASP Inactive Ack
             message from its peer.

  M-ASP_INACTIVE indication
  Direction: TUA -> LM
  Purpose:   TUA reports it has successfully processed an incoming ASP
             Inactive message from its peer.

  M-AS_ACTIVE indication
  Direction: TUA -> LM
  Purpose:   TUA reports that an AS has moved to the AS-ACTIVE state.

  M-AS_INACTIVE indication
  Direction: TUA -> LM
  Purpose:   UA reports that an AS has moved to the AS-INACTIVE state.

  M-AS_DOWN indication
  Direction: TUA -> LM
  Purpose:   UA reports that an AS has moved to the AS-DOWN state.

  M-RK_REG request
  Direction: LM -> TUA
  Purpose:   LM requests ASP to register RK(s) with its peer by
             sending REG REQ message

  M-RK_REG confirm
  Direction: TUA -> LM
  Purpose:   ASP reports that it has received REG RSP message with
             registration status as successful from its peer.

  M-RK_REG indication
  Direction: TUA -> LM
  Purpose:   TUA informs LM that it has successfully processed an
             incoming REG REQ message.

  M-RK_DEREG request
  Direction: LM -> TUA
  Purpose:   LM requests ASP to deregister RK(s) with its peer by
             sending DEREG REQ message.

  M-RK_DEREG confirm
  Direction: TUA -> LM
  Purpose:   ASP reports that it has received DEREG REQ message with
             deregistration status as successful from its peer.

  M-RK_DEREG indication
  Direction: TUA -> LM

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  Purpose:   TUA informs LM that it has successfully processed an
             incoming DEREG REQ from its peer.

1.5.3.  Definition of the Lower Boundary

  The upper layer primitives provided by the SCTP are provided in the
  SCTP specification "Stream Control Transmission Protocol (SCTP)" [RFC
  2960].

2.  Conventions

  The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
  SHOULD NOT, RECOMMENDED, NOT RECOMMENDED, MAY, and OPTIONAL, when they
  appear in this document, are to be interpreted as described in [RFC
  2119].

  In this document, the following conventions are used to describe how a
  parameter is used in the message:

    Mandatory     The parameter MUST be present in the message.  A
                  message listing a parameter as Mandatory without
                  containing such a parameter is is incorrectly
                  formatted.

    Conditional   The parameter SHOULD be present in the message
                  under the conditions specified.  A message listing
                  a parameter as Conditional without containing such
                  a parameter under the conditions specified is
                  incorrectly formatted.

    Optional      The parameter MAY be present in the message as
                  specified.  A message listing a parameter as
                  Optional without containing such a parameter is
                  correctly formatted.

3.  Protocol Elements

  The general message format includes a Common Message Header together
  with a list of zero or more parameters as defined by the Message Type.

  For forward compatibility, all Message Types MAY have attached
  parameters even if none are specified in this version.

3.1.  Common Message Header

  The protocol messages for the TCAP-User Adaptation Protocol (TUA)
  require a message structure that contains a version, message type,
  message length and message contents:

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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |    Version    |   Reserved    | Message Class | Message Type  |
    +---------------+---------------+---------------+---------------+
    |                        Message Length                         |
    +---------------------------------------------------------------+
    |                         Message Data                          |

  Notes:

   o This message header is common among all signalling protocol
     adaptation layers.
   o The 'data' portion of TUA messages SHALL contain zero or more TUA
     parameters, and SHALL NOT contain an encapsulated TCAP message.
   o All fields in the TUA message MUST be transmitted in the network
     byte order, unless otherwise stated.

3.1.1.  TUA Protocol Version

  Version: 8-bits (unsigned integer)

    The Version field of the Common Message Header contains the version
    of the TUA adaptation layer.  The supported versions are:

        1 - TUA Version 1.0

3.1.2.  Message Classes

  Message Class: 8-bits (unsigned integer)

    The Message Class field of the Common Message Header contains the
    class of the message.  The supported classes are as follows:

      0        Management (MGMT) Message
      7        Reserved for Other Signalling Adaptation Layers
      2        SS7 Signalling Network Management (SSNM) Messages
      3        ASP State Maintenance (ASPSM) Messages
      4        ASP Traffic Maintenance (ASPTM) Messages
      5        TUA Dialogue Handling (DH) Messages
      6        TUA Component Handling (CH) Messages
      7        Reserved for Other Signalling Adaptation Layers
      8        Reserved for Other Signalling Adaptation Layers
      9        Routing key Management (RKM) Messages
     10 - 127  Reserved by the IETF
    128 - 255  Reserved for IETF-Defined Message Class Extensions

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3.1.3.  Message Types

  Message Type: 8-bits (unsigned integer)

    The Message Type field of the Common Message Header contains the
    type of message within a message class.  The supported types of
    messages within the supported classes are as follows:

    Management (MGMT) Messages
      0         Error (ERR)
      1         Notify (NTFY)
      2 -  127  Reserved by the IETF
    128 -  255  Reserved for IETF-Defined Message Class Extensions

    SS7 Signalling Network Management (SSNM) Messages
      0         Reserved
      1         Destination Unavailable (DUNA)
      2         Destination Available (DAVA)
      3         Destination State Audit (DAUD)
      4         Destination Congestion (SCON)
      5         Destination User Part Unavailable (DUPU)
      6         Destination Restricted (DRST)
      7 -  127  Reserved by the IETF
    128 -  255  Reserved for IETF-Defined Message Class Extensions

    Application Server Process State Maintenance (ASPSM) Messages
      0         Reserved
      1         ASP Up (UP)
      2         ASP Down (DOWN)
      3         Heartbeat (BEAT)
      4         ASP Up Ack (UP ACK)
      5         ASP Down Ack (DOWN ACK)
      6         Heartbeat Ack (BEAT ACK)
      7 -  127  Reserved by the IETF
    128 -  255  Reserved for IETF-Defined Message Class Extensions

    Application Server Process Traffic Maintenance (ASPTM) Messages
      0         Reserved
      1         ASP Active (ASPAC)
      2         ASP Inactive (ASPIA)
      3         ASP Active Ack (ASPAC ACK)
      4         ASP Inactive Ack (ASPIA ACK)
      5 -  127  Reserved by the IETF
    128 -  255  Reserved for IETF-Defined Message Class Extensions

    Routing Key Management (RKM) Messages
      0         Reserved
      1         Registration Request (REG REQ)
      2         Registration Response (REG RSP)
      3         Deregistration Request (DEREG REQ)
      4         Deregistration Response (DEREG RSP)

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      5 -  127  Reserved by the IETF
    128 -  255  Reserved for IETF-Defined Message Class Extensions

    TUA Dialogue Handling (DH) Messages
      0         Unidirectional(TUNI)
      1         Query (TQRY)
      2         Conversation (TCNV)
      3         Response (TRSP)
      4         U-Abort (TUAB)
      5         P-Abort (TPAB)
      6         Notice (TNOT)
      7 -  127  Reserved by the IETF
    128 -  255  Reserved for IETF-Defined Message Class Extensions

    TUA Component Handling (CH) Messages
      1         Invoke (CINV)
      2         Result (CRES)
      3         Error (CERR)
      4         Reject (CREJ)
      5         Cancel (CCAN)
      6 -  127  Reserved by the IETF
    128 -  255  Reserved for IETF-Defined Message Class Extensions

3.1.4.  Message Length

  Message Length: 32-bits (unsigned integer)

    The Message Length field of the Common Message Header defines the
    length of the message in octets, including the header.

3.1.5.  Tag-Length-Value Format

  TUA messages consist of a Common Message Header followed by zero or
  more parameters, as defined by the message type.  The Tag-Length-Value
  (TLV) parameters contained in a message are defined in a Tag-Length-
  Value format as shown below [4].

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Parameter Tag        |       Parameter Length        |
    +-------------------------------+-------------------------------+
    \                                                               \
    /                       Parameter Value                         /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  Parameter Tag: 16-bits (unsigned integer)
    The Parameter Tag field is a 16-bit identifier of the type of
    parameter.  It takes a value of 0 to 65534.

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  Parameter Length: 16-bits (unsigned integer)
    The Parameter Length field contains the size of the parameter in
    bytes, including the Parameter Tag, Parameter Length, and Parameter
    Value fields.  The Parameter Length does not include any padding
    bytes.

  Parameter Value: variable-length
    The Parameter Value field contains the actual information to be
    transferred in the parameter.  The total length of a parameter
    (including Tag, Parameter Length and Value fields) MUST be a
    multiple of 4 bytes.  If the length of the parameter is not a
    multiple of 4 bytes, the sender MUST pad the Parameter at the end
    (i.e., after the Parameter Value field) with all zero bytes.  The
    length of the padding MUST NOT be included in the parameter length
    field.  A sender SHOULD NOT pad with more than 3 bytes.  The
    receiver MUST ignore the padding bytes.

3.2.  TUA Message Header

  In addition to the Common Message Header, a specific message header is
  included for TUA messages.  The TUA message header will immediately
  follow the Common Message Header in TUA Dialogue Handling (DH) and
  Component Handling (CH) messages.

  The TUA Message Header is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0006          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                        Routing Context                        |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0013          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                        Correlation Id                         |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0401          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                          Dialogue Id                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The TUA Message header can contain the following parameters:

      Parameters
      ---------------------------------------------
      Routing Context             Conditional   *1
      Correlation Id              Conditional   *2
      Dialogue Id                 Conditional   *3

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  Note 1: When an ASP is registered or configured for multiple AS with
          an SG, the Routing Context MUST be present in the TUA Message
          Header.  The Routing Context SHOULD always be placed in the
          TUA Message Header.  When the Routing Context is present in
          the TUA Message Header it SHOULD be placed first in the header
          because the context of the Dialogue Id depends on the Routing
          Context.

  Note 2: Under some circumstances, the Correlation Id parameter MUST be
          included in the TUA Message Header.  See sections "Correlation
          Id" and "ASP Active Procedures".

  Note 3: When an AS is handling multiple Dialogues, the Dialogue Id
          parameter MUST be placed in the TUA Message Header.  The
          Dialogue Id parameter SHOULD always be placed in the TUA
          Message Header.  The Dialogue Id parameter MAY be excluded
          from the TUA header for TUNI and TPAB DH messages, or may be
          included but then MUST contain a value of zero.

3.3.  TUA Dialogue Handling (DH) Messages

  The following section describes the TUA Dialogue Handling (DH)
  messages and parameter contents.  The general message format includes
  a Common Message Header, the TUA Message Header and the DH Message
  Header, together with a list of zero or more parameters as defined by
  the Message Type.  For forward compatibility, all Message Types MAY
  have optional attached parameters in addition to the message headers.

3.3.1.  DH Message Header

  In addition to the Common Message Header and TUA Message Header, a
  specific message header is included for TUA Dialogue Handling (DH)
  messages.  The DH Message Header will immediately follow the TUA
  Message header in these messages.

  The DH Message Header is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0402          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                         Dialogue Flags                        |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0403          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                       Quality of Service                      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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  The DH Message header contains the following parameters:

      Parameters
      ------------------------------------------
      Dialogue Flags              Mandatory
      Quality of Service          Mandatory

3.3.2.  Unidirectional (TUNI)

  The Unidirectional (TUNI) Request message is sent from an ASP to an SG
  or IPSP to invoke a TCAP class 4 operation.  The TUNI Indication
  message is sent from an SGP to an ASP to indicate the TCAP class 4
  operation.

  The TUNI message corresponds to the ITU-T `TC-UNI' primitive [Q.771],
  and the ITU-T and ANSI `Unidirectional' message [Q.773, T1.114].

  The TUNI message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0404          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                      Destination Address                      /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0405          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                      Originating Address                      /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0406          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                    Application Context Name                   /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0407          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        User Information                       /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0408          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Security Context                       /
    \                                                               \

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    +-------------------------------+-------------------------------+
    |         Tag = 0x0409          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Confidentiality                        /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x040E          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                           Components                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The TUNI message can contain the following parameters:

      Parameters
      ---------------------------------------------
      Destination Address         Conditional   *1
      Originating Address         Conditional   *1
      Application Context Name    Optional
      User Information            Optional
      Security Context            Optional
      Confidentiality             Optional
      Components                  Optional      *2

  Note 1: The Destination Address or Originating Address parameter MUST
          be present in the TUNI message when either parameter is not
          implied by the Routing Context in the TUA Message Header.

  Note 2: Any components SHOULD be included in the TUNI messages but MAY
          be formatted in separate TUA Component Handling (CH) messages.

3.3.3.  Query (TQRY)

  The Query (TQRY) message is sent to a TUA peer to begin a new dialogue
  between TC-Users.

  The TQRY message corresponds to the ITU-T `TC-BEGIN' primitive
  [Q.771], the ITU-T `Begin' message [Q.773] and the ANSI `Query'
  message [T1.114].

  The TQRY message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0410          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                         Transaction Id                        |
    +-------------------------------+-------------------------------+

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    |         Tag = 0x0404          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                      Destination Address                      /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0405          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                      Originating Address                      /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0406          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                    Application Context Name                   /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0407          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        User Information                       /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0408          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Security Context                       /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0409          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Confidentiality                        /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x040E          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                           Components                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The TQRY message can contain the following parameters:

      Parameters
      ---------------------------------------------
      Transaction Id              Mandatory
      Destination Address         Conditional   *1
      Originating Address         Conditional   *1

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      Application Context Name    Optional
      User Information            Optional
      Security Context            Optional
      Confidentiality             Optional
      Components                  Optional      *2

  Note 1: The Destination Address or Originating Address parameter MUST
          be present in the TQRY message when the parameter is not
          implied by the Routing Context in the TUA Message Header.

  Note 2: Any components SHOULD be included in the TQRY messages but MAY
          be formatted in separate Component Handling (CH) messages.

3.3.4.  Conversation (TCNV)

  The Conversation (TCNV) message is used in response to a TQRY message
  or another TCNV message.

  When sent in response to a TQRY message, the TCNV message confirms and
  continues a dialogue; when in response to a received TCNV message, it
  only continues a dialogue.  The Dialogue Flags in the DH Message
  Header indicate whether the initiator of the TCNV message give
  permission to the peer to terminate the dialogue.

  The TCNV message corresponds to the ITU-T `TC-CONTINUE' primitive
  [Q.771], ITU-T `Continue' message [Q.773] and the ANSI `Conversation'
  message [T1.114].

  The TCNV message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0410          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                         Transaction Id                        |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0405          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                      Originating Address                      /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0406          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                    Application Context Name                   /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0407          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \

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    /                        User Information                       /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0408          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Security Context                       /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0409          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Confidentiality                        /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x040E          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                           Components                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The TCNV message can contain the following parameters:

      Parameters
      ---------------------------------------------
      Transaction Id              Conditional   *1
      Originating Address         Conditional   *2
      Application Context Name    Conditional   *3
      User Information            Conditional   *3
      Security Context            Conditional   *3
      Confidentiality             Conditional   *3
      Components                  Optional      *4

  Note 1: The Transaction Id parameter MUST be present in the TCNV
          message when the message is sent in response to a TQUR
          message.  The Transaction Id parameter contains the
          Transaction Identifier assigned by the remote TC-User.

  Note 2: The Originating Address parameter MUST be present in the TCNV
          message when the message is used in response to a TQRY message
          and the parameter is not implied by the Routing Context in the
          TUA Message Header.

  Note 3: These dialogue portion parameters SHOULD only be optionally
          included in the TCNV message when the message is used in
          response to a TQRY message.  When the TCNV message is sent in
          response to a received TCNV message, these parameters SHOULD
          NOT be included in the responding TCNV message.

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  Note 4: Any components SHOULD be included in the TCNV messages but MAY
          be formatted in separate Component Handling (CH) messages.

3.3.5.  Response (TRSP)

  The Response (TRSP) message is used in response to a TQRY message or
  TCNV message to complete and existing dialogue.

  When sent in response to a TQRY message, the TRSP message confirms and
  completes a dialogue; when in response to a received TCNV message, it
  only terminates a dialogue.

  The TRSP message corresponds to the ITU-T `TC-END' primitive [Q.771],
  ITU-T `End' message [Q.773] and the ANSI `Response' message [T1.114].

  The TRSP message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x040A          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                          Termination                          |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0406          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                    Application Context Name                   /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0407          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        User Information                       /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0408          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Security Context                       /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0409          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Confidentiality                        /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x040E          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                           Components                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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  The TRSP message can contain the following parameters:

      Parameters
      -------------------------------------------
      Termination                 Mandatory
      Application Context Name    Optional    *1
      User Information            Optional    *1
      Security Context            Optional    *1
      Confidentiality             Optional    *1
      Components                  Optional    *2

  Note 1: These dialogue portion parameters SHOULD only be optionally
          included in the TRSP message when it is issued in response to
          an TQRY message.  When the TRSP message is in response to a
          TCNV message, the dialogue portion parameters SHOULD NOT be
          included in the TRSP message.

  Note 2: Any components SHOULD be included in the TRSP messages but MAY
          be formatted in separate TUA Component Handling (CH) messages.

3.3.6.  U-Abort (TUAB)

  The TUA peer sends an U-Abort (TUAB) message when it wishes to abort a
  dialogue, either under TUA-user control (TC-U-ABORT).

  When sent in response to a TQRY message, the TUAB message negatively
  confirms and aborts a dialogue; when in response to a received TCNV
  message, it only aborts a dialogue.

  The TUAB message corresponds to the ITU-T `TC-U-ABORT' primitive
  [Q.771], the ITU-T `Abort' message [Q.773] and the ANSI `Abort'
  message [T1.114].

  The TUAB message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x040D          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                         Abort Reason                          |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0405          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                      Originating Address                      /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0406          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                    Application Context Name                   /

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    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0407          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        User Information                       /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The TUAB message can contain the following parameters:

      Parameters
      ---------------------------------------------
      Abort Reason                Mandatory
      Application Context Name    Conditional   *1
      User Information            Optional      *2

  Note 1: These dialogue portion parameters SHOULD only be optionally
          included in the TUAB message when it is issued in response to
          an TQRY message.  When the TUAB message is in response to a
          TCNV message, the dialogue portion parameters SHOULD NOT be
          included in the TUAB message.

  Note 2: The User Information parameter carries any User Abort
          Information.

3.3.7.  P-Abort (TPAB)

  The TUA peer sends an P-Abort (TPAB) message when it wishes to abort a
  dialogue, either under TUA control (TC-P-ABORT).

  The TPAB message corresponds to the ITU-T `TC-P-ABORT' primitive
  [Q.771], the ITU-T `Abort' message [Q.773] and the ANSI `Abort'
  message [T1.114].

  The TPAB message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x040B          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                          Abort Cause                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The TPAB message can contain the following parameters:

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      Parameters
      ------------------------------------------
      Abort Cause                 Mandatory

3.3.8.  Notice (TNOT)

  An SG sends a Notice (TNOT) message when it wishes to inform the ASP
  of a network condition that concerns the transmission of TCAP or TUA
  messages to the remote TC-User in a dialogue [Q.775].  It is used at
  the SG when an SCCP message containing TC-User information from an AS
  has been returned in a UDTS when the "Return Option" flag was set in
  the Quality of Service parameters when the message was sent.

  The TNOT message corresponds to the ITU-T [Q.771] TC-NOTICE primitive.

  The TNOT message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x040C          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                          Report Cause                         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The TNOT message can contain the following parameters:

      Parameters
      ------------------------------------------
      Report cause                Mandatory

3.4.  TUA Component Handling (CH) Messages

  The following section describes the TUA Component Handling messages
  and parameter contents.  The general message format includes a Common
  Message Header, a TUA Message Header, a CH Message Header, followed by
  a list of zero or more parameters as defined by the Message Type.  For
  forward compatibility, all Message Types MAY have attached optional
  parameters in addition to the message headers.

  Component Handling (CH) messages are used to convey components
  associated with operations within a dialogue.  They are issued prior
  to the Dialogue Handling (DH) message with which they are associated,
  but are received after receiving a Dialogue Handling (DH) message that
  has the "Components Present" bit set in the Dialogue Flags parameter
  within the DH message.

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3.4.1.  CH Message Header

  In addition to the Common Message Header and TUA Message Header, a
  specific message header is included for TUA Component Handling (CH)
  messages.  The CH Message Header will immediately follow the TUA
  Message Header in these messages.

  The CH Message Header if formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0411          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                           Invoke Id                           |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0412          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                           Linked Id                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The CH Message Header can contain the following parameters:

      Parameters
      ------------------------------------------
      Invoke Id                   Mandatory
      Linked Id                   Optional

3.4.2.  Invoke (CINV)

  The Invoke (CINV) message is used to invoke an operation within a
  dialogue.

  The CINV message corresponds to the ITU-T `TC-INVOKE' primitive
  [Q.771], the ITU-T `Invoke' component [Q.773], and the ANSI `Invoke
  (Last)' and `Invoke (Not Last)' components [T1.114].

  The CINV message is formatted as follows:

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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0413          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                        Component Flags                        |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0418          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                            Timeout                            |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0414          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                           Operation                           /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0415          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                           Parameters                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The CINV message can contain the following parameters:

      Parameters
      -------------------------------------------
      Component Flags             Mandatory   *1
      Timeout                     Mandatory
      Operation                   Mandatory
      Parameters                  Optional

  Note 1: The Component Flags parameter MAY be ignored by the receiver
          of the CINV message for ITU-T protocol variants of TC-Users
          that do not support the concept of a "Not Last" TC-INVOKE
          primitive.

3.4.3.  Result (CRES)

  The Result (CRES) message is used to report the successful completion
  of an operation within a dialogue.

  The CRES message corresponds to the ITU-T `TC-RESULT-L' and `TC-
  RESULT-NL' primitives [Q.771], the ITU-T `Return Result (Last)' and
  `Return Result (Not Last)' components [Q.773] and the ANSI `Return
  Result (Last)' and `Return Result (Not Last)' components.

  The CRES message is formatted as follows:

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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0413          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                        Component Flags                        |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0414          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                           Operation                           /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0415          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                           Parameters                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The CRES message can contain the following parameters:

      Parameters
      ---------------------------------------------
      Component Flags             Mandatory
      Operation                   Conditional   *1
      Parameters                  Optional

  Note 1: The Operation parameter MUST be present in the CRES message
          when the Parameters parameter is also present.

3.4.4.  Error (CERR)

  The Error (CERR) message is used to report the failure of an operation
  within a dialogue.

  The CERR message corresponds to the ITU-T `TC-U-ERROR' primitive
  [Q.771], the ITU-T `Return Error' component [Q.773] and the ANSI
  `Return Error' component [T1.114].

  The CERR message is formatted as follows:

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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0416          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                             Error                             /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0415          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                           Parameters                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The CERR message can contain the following parameters:

      Parameters
      ---------------------------------------------
      Error                       Mandatory
      Parameters                  Conditional   *1

  Note 1: The Parameters parameter is only included in the message for
          specific error codes.

3.4.5.  Reject (CREJ)

  The Reject (CREJ) message is used to reject an operation within a
  dialogue.

  The CREJ message corresponds to the ITU-T `TC-L-REJECT', `TC-R-REJECT'
  and `TC-U-REJECT' primitives [Q.771], the ITU-T `Reject' component
  [Q.773] and the ANSI `Reject' component [T1.114].

  The CREJ message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0417          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                          Problem Code                         /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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  The CREJ message can contain the following parameters:

      Parameters
      ------------------------------------------
      Problem Code                Mandatory

3.4.6.  Cancel (CCAN)

  The Cancel (CCAN) message is used to cancel an operation within a
  dialogue.i

  The CCAN message corresponds to the ITU-T `TC-L-CANCEL' and `TC-U-
  CANCEL' primitives [Q.771].

  The CCAN message presently contains no Message-Type-specific
  parameters.

3.5.  SS7 Signalling Network Management (SSNM) Messages

  SS7 Signalling Network Management (SSNM) Messages are used to convey
  network management information to the TC-User.  Theses messages
  correspond to specific N-STATE, N-PCSTATE and N-COORD primitives.

3.5.1.  Destination Unavailable (DUNA)

  The Destination Unavailable (DUNA) message is sent from an SGP to all
  concerned ASPs to indicate the unavailability of an SS7 SCCP subsystem
  or signalling point.  The TC-User at the ASP is expected to stop
  traffic to TC-User peers at the affected subsystems or signalling
  points via the SG initiating the DUNA message.

  When the DUNA message contains the Subsystem Number parameter, the
  message corresponds to the ITU-T [Q.711] and ANSI [T1.112] `N-STATE'
  primitive.  When the DUNA message does not contain the Subsystem
  Number parameter, message, the message corresponds to the ITU-T
  [Q.711] and ANSI [T1.112] `N-PCSTATE' primitive.

  The DUNA message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0006          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Routing Context                        /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0012          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \

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    /                       Affected Point Code                     /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0419          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                         Subsystem Number                      |
    +-------------------------------+-------------------------------+
    |         Tag = 0x041A          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                 Subsystem Multiplicity Indicator              |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0004          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                           Info String                         /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The DUNA message can contain the following parameters:

      Parameters
      ----------------------------------------------------
      Routing Context                    Mandatory
      Affected Point Code                Mandatory
      Subsystem Number                   Conditional   *1
      Subsystem Multiplicity Indicator   Optional      *2
      Info String                        Optional

  Note 1: The Subsystem Number parameter SHALL be present in the DUNA
          message when indicating the unavailability of a subsystem, and
          SHALL NOT be present when indicating the unavailability of a
          signalling point.

  Note 2: The Subsystem Multiplicity Indicator parameter SHOULD NOT be
          present in the DUNA message when the Subsystem Number
          parameter is not also present.

3.5.2.  Destination Available (DAVA)

  The Destination Available (DAVA) message is sent from an SGP to all
  concerned ASPs to indicate the availability of an SS7 SCCP Subsystem
  or signalling point.  The TC-User at the ASP is expected to resume
  traffic to TC-Users peers at the affected subsystems or signalling
  points via the SG initiating the DAVA message.

  When the DAVA message contains the Subsystem Number parameter, the
  message corresponds to the ITU-T [Q.711] and ANSI [T1.112] `N-STATE'
  primitive.  When the DAVA message does not contain the Subsystem
  Number parameter, message, the message corresponds to the ITU-T
  [Q.711] and ANSI [T1.112] `N-PCSTATE' primitive.

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  The DAVA message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0006          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Routing Context                        /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0012          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                       Affected Point Code                     /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0419          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                         Subsystem Number                      |
    +-------------------------------+-------------------------------+
    |         Tag = 0x041A          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                 Subsystem Multiplicity Indicator              |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0004          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                           Info String                         /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The DAVA message can contain the following parameters:

      Parameters
      ----------------------------------------------------
      Routing Context                    Mandatory
      Affected Point Code                Mandatory
      Subsystem Number                   Conditional   *1
      Subsystem Multiplicity Indicator   Optional      *2
      Info String                        Optional

  Note 1: The Subsystem Number parameter SHALL be present in the DAVA
          message when indicating the availability of a subsystem, and
          SHALL NOT be present when indicating the availability of a
          signalling point.

  Note 2: The Subsystem Multiplicity Indicator parameter SHOULD NOT be
          present in the DAVA message when the Subsystem Number
          parameter is not also present.

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3.5.3.  Destination State Audit (DAUD)

  The Destination State Audit (DAUD) message is sent from an ASP to an
  SG to query the availability state of routes to SS7 SCCP subsystems or
  signalling points.  A DAUD message MAY be sent periodically after the
  ASP has received a DUNA message, and until a DAVA is received for the
  affected subsystem or signalling point.  The DAUD message can also be
  sent when an ASP recovers from isolation from the SG.

  When the DAVA message contains the Subsystem Number parameter, the
  message is soliciting responses that correspond to the ITU-T [Q.711]
  and ANSI [T1.112] `N-STATE' primitive.  When the DAVA message does not
  contain the Subsystem Number parameter, message, the message
  soliciting responses that correspond to the ITU-T [Q.711] and ANSI
  [T1.112] `N-PCSTATE' primitive.

  The DAUD message is formatted as follows:

     0                     1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0006          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Routing Context                        /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0012          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                       Affected Point Code                     /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0419          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                         Subsystem Number                      |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0004          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                           Info String                         /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The DAUD message can contain the following parameters:

      Parameters
      ---------------------------------------------
      Routing Context             Mandatory
      Affected Point Code         Mandatory

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      Subsystem Number            Conditional   *1
      Info String                 Optional

  Note 1: The Subsystem Number parameter SHALL be present in the DAVA
          message when auditing the status of a subsystem, and SHALL NOT
          be present when auditing the status of a signalling point.

3.5.4.  Network Congestion (SCON)

  The Network Congestion (SCON) message is sent from an SG to all
  concerned ASPs to indicate that the congestion level in the SS7
  network to a specified subsystem or signalling point has changed. The
  TC-User at the ASP is expected to stop traffic at the indicated
  importance level to TC-User peers at the affected subsystems or
  signalling points via the SG initiating the SCON message.

  When the SCON message contains the Subsystem Number parameter, the
  message corresponds to the ITU-T [Q.711] and ANSI [T1.112] `N-STATE'
  primitive.  When the SCON message does not contain the Subsystem
  Number parameter, message, the message corresponds to the ITU-T
  [Q.711] and ANSI [T1.112] `N-PCSTATE' primitive.

  The SCON message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0006          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Routing Context                        /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0012          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                       Affected Point Code                     /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x041B          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                         Congestion Level                      |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0419          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                         Subsystem Number                      |
    +-------------------------------+-------------------------------+
    |         Tag = 0x041A          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                 Subsystem Multiplicity Indicator              |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0004          |            Length             |

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    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                           Info String                         /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The SCON message can contain the following parameters:

      Parameters
      --------------------------------------------------
      Routing Context                    Mandatory
      Affected Point Code                Mandatory
      Congestion Level                   Mandatory
      Subsystem Number                   Optional    *1
      Subsystem Multiplicity Indicator   Optional    *2
      Info String                        Optional

  Note 1: The Subsystem Number parameter SHALL be present in the SCON
          message when indicating the congestion of a subsystem, and
          SHALL NOT be present when indicating the congestion of a
          signalling point.

  Note 2: The Subsystem Multiplicity Indicator parameter SHOULD NOT be
          present in the SCON message when the Subsystem Number
          parameter is not also present.

3.5.5.  Destination User Part Unavailable (DUPU)

  The Destination User Part Unavailable (DUPU) message is sent from an
  SG to all concerned ASPs to indicate the unavailability of an SS7
  SCCP.

  The DUPU message corresponds to the ITU [Q.711] and ANSI [T1.112] `N-
  PCSTATE' primitive.

  The DUPU message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0006          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Routing Context                        /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0012          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                       Affected Point Code                     /
    \                                                               \

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    +-------------------------------+-------------------------------+
    |         Tag = 0x041C          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                           User/Cause                          |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0004          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                           Info String                         /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The DUPU message can contain the following parameters:

      Parameters
      -------------------------------------------
      Routing Context             Mandatory
      Affected Point Code         Mandatory
      User/Cause                  Mandatory   *1
      Info String                 Optional

  Note 1: The User field of the )User/Cause parameter must indicate an
          SCCP MTP-User part and can be ignored by the receiver of the
          DUPU message.

3.5.6.  Destination Restricted (DRST)

  The Destination Restricted (DRST) message is sent from an SG to all
  concerned ASPs to indicate one of the following:

   (1)   A replicated subsystem is requesting that the TUA layer at the
         ASP accept transactions for the affected subsystem.  The TUA
         layer at the ASP is expected to determine whether it can accept
         the traffic of the affected subsystem and respond with a DRST
         message.

   (2)   An SG representing a signalling transfer point is requesting
         that the TUA layer at the ASP routing message traffic via an
         alternate SG if possible.

  The DRST is sent from an ASP to an SG in response to a DRST from the
  SG when the TUA layer at the ASP is prepared to accept traffic for the
  affected subsystem.

  When the DRST message contains the Subsystem Number parameter, this
  message corresponds to the ITU [Q.711] and ANSI [T1.112] `N-COORD'
  primitive.  When the DRST message contains the Subsystem Multiplicity
  Indicator parameter, the message corresponds to the `Request' and
  `Indication' forms of the `N-COORD' primitive; when it dos not include
  the parameter, it corresponds to the `Response' and `Confirm' forms of
  the `N-COORD' primitive.

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  When the DRST message does not contain the Subsystem Number parameter,
  the message corresponds to the ITU [Q.704] and ANSI [T1.111] `Transfer
  Restricted' message.

  The DRST message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0006          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Routing Context                        /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0012          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                       Affected Point Code                     /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0419          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                         Subsystem Number                      |
    +-------------------------------+-------------------------------+
    |         Tag = 0x041A          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                 Subsystem Multiplicity Indicator              |
    +-------------------------------+-------------------------------+
    \                                                               \
    /                           Info String                         /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The DRST message can contain the following parameters:

      Parameters
      ----------------------------------------------------
      Routing Context                    Mandatory
      Affected Point Code                Mandatory     *1
      Subsystem Number                   Conditional   *2
      Subsystem Multiplicity Indicator   Conditional   *3
      Info String                        Optional

  Note 1: The Affected Point Code refers to the node which has become
          restricted or which has requested coordinated service outage.

  Note 2: The Subsystem Number parameter SHALL be present in the SCON
          message when requesting or responding to a subsystem
          coordinated service outage, and SHALL NOT be present when
          indicating the restriction of a signalling point.

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  Note 3: The Subsystem Multiplicity Indicator parameter SHOULD NOT be
          present in the SCON message when the Subsystem Number
          parameter is not also present.  The Subsystem Multiplicity
          Indicator parameter SHALL be present in the SCON message when
          requesting or indicating a coordinated service outage, and
          SHALL NOT be present when responding to or confirming a
          coordinated service outage.

3.6.  Application Server Process State Maintenance (ASPSM) Messages

3.6.1.  ASP Up (UP)

  The ASP Up (UP) message is used to indicate to a remote TUA peer that
  the Adaptation layer is up and running.

  The ASP UP message is formatted as follows:

     0                     1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0011          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                        ASP Identifier                         |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0004          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                          Info String                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The ASP UP message can contain the following parameters:

      Parameters
      ---------------------------------------------
      ASP Identifier              Conditional   *1
      Info String                 Optional

  Note 1: ASP Identifier MUST be used where the IPSP/SGP cannot identify
          the ASP by pre-configured address/port number information
          (e.g, where an ASP is resident on a Host using dynamic
          address/port number assignment).

3.6.2.  ASP Up Ack (UP ACK)

  The ASP Up Ack (UP ACK) message is used to acknowledge an ASP UP
  message received from a remote TUA peer.

  The ASP UP ACK message is formatted as follows:

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     0                     1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0004          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                          Info String                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The ASP UP ACK message can contain the following parameters:

      Parameters
      -----------------------------------------
      Info String                 Optional

3.6.3.  ASP Down (DOWN)

  The ASP Down (DOWN) message is used to indicate to a remote TUA peer
  that the adaptation layer is not running.

  The ASP DOWN message is formatted as follows:

     0                     1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0004          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                          Info String                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The ASP DOWN message can contain the following parameters:

      Parameters
      -----------------------------------------
      Info String                 Optional

3.6.4.  ASP Down Ack (DOWN ACK)

  The ASP Down Ack (DOWN ACK) message is used to acknowledge an ASP DOWN
  message received from a remote TUA peer.

  The ASP DOWN ACK message is formatted as follows:

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     0                     1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0004          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                          Info String                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The ASP DOWN ACK message can contain the following parameters:

      Parameters
      -----------------------------------------
      Info String                 Optional

  Note:   The ASP DOWN ACK message will always be sent to acknowledge an
          ASP DOWN message.

3.6.5.  Heartbeat (BEAT)

  The Heartbeat (BEAT) message is optionally used to ensure that the TUA
  peers are still available to each other.

  The BEAT message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0009          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                         Heartbeat Data                        /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The BEAT message can contain the following parameters:

      Parameters
      -----------------------------------------
      Heartbeat Data              Optional

3.6.6.  Heartbeat Ack (BEAT ACK)

  The Heartbeat ACK (BEAT ACK) message is sent in response to a BEAT
  message.  A peer MUST send a BEAT ACK in response to a BEAT message.
  It includes all the parameters of the received BEAT message, without
  any change.

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  The BEAT ACK message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0009          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                         Heartbeat Data                        /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The BEAT ACK message can contain the following parameters:

      Parameters
      -----------------------------------------
      Heartbeat Data              Optional

3.7.  Application Server Process Traffic Maintenance (ASPTM) Messages

3.7.1.  ASP Active (ASPAC)

  The ASP Active (ASPAC) message is sent by an ASP to indicate to a
  remote TUA peer that it is Active and ready to process signalling
  traffic for a particular Application Server.

  The ASPAC message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0006          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                       Routing Context                         /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x000B          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                       Traffic Mode Type                       |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0004          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                          Info String                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The ASPAC message can contain the following parameters:

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      Parameters
      ---------------------------------------------
      Routing Context             Conditional   *1
      Traffic Mode Type           Optional      *2
      Info String                 Optional

  Note 1: When an ASP is registered or configured for multiple AS with
          an SG, the Routing Context associated with the AS whose
          activation is being requested MUST be placed in the ASPAC
          message.

  Note 2: The Traffic Mode Type parameter is not necessary in the ASPAC
          message when both peers are aware of the traffic mode of the
          AS by configuration or registration.

3.7.2.  ASP Active Ack (ASPAC ACK)

  The ASP Active Ack (ASPAC) Ack message is used to acknowledge an ASPAC
  message received from a remote TUA peer.

  The ASPAC ACK message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0006          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                       Routing Context                         /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x000B          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                       Traffic Mode Type                       |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0004          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                          Info String                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The ASPAC ACK message can contain the following parameters:

      Parameters
      ---------------------------------------------
      Routing Context             Conditional   *1
      Traffic Mode Type           Optional
      Info String                 Optional

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  Note 1: When an ASP is registered or configured for multiple AS with
          an SG, the Routing Context associated with the AS whose
          activation is being acknowledged MUST be placed in the ASPAC
          ACK message.

3.7.3.  ASP Inactive (ASPIA)

  The ASP Inactive (ASPIA) message is sent by an ASP to indicate to a
  remote TUA peer that it is no longer processing signalling traffic
  within a particular Application Server.

  The ASPIA message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0006          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                       Routing Context                         /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0004          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                          INFO String                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The ASPIA message can contain the following parameters:

      Parameters
      ---------------------------------------------
      Routing Context             Conditional   *1
      INFO String                 Optional

  Note 1: When an ASP is registered or configured for multiple AS with
          an SG, the Routing Context associated with the AS whose
          deactivation is being requested MUST be placed in the ASPIA
          message.

3.7.4.  ASP Inactive Ack (ASPIA ACK)

  The ASP Inactive Ack (ASPIA ACK) message is used to acknowledge an
  ASPIA message received from a remote TUA peer.

  The ASPIA message is formatted as follows:

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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0006          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                       Routing Context                         /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0004          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                          INFO String                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The ASPIA message can contain the following parameters:

      Parameters
      ---------------------------------------------
      Routing Context             Conditional   *1
      INFO String                 Optional

  Note 1: When an ASP is registered or configured for multiple AS with
          an SG, the Routing Context associated with the AS whose
          deactivation is being acknowledged MUST be placed in the ASPIA
          ACK message.

3.8.  Management (MGMT) Messages

3.8.1.  Error (ERR)

  The Error (ERR) message is used by a TUA peer to indicate an error
  situation.  ERR messages MUST NOT be generated in response to other
  ERR messages.

  The ERR message is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x000C          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                          Error Code                           |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0006          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                         Routing Context                       /
    \                                                               \
    +-------------------------------+-------------------------------+

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    |         Tag = 0x0012          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                       Affected Point Code                     /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0419          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                        Subsystem Number                       |
    +-------------------------------+-------------------------------+
    |         Tag = 0x041D          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                       Network Appearance                      |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0007          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                         Diagnostic Info                       /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The ERR message can contain the following parameters:

      Parameters
      ---------------------------------------------
      Error Code                  Mandatory
      Routing Context             Conditional   *1
      Affected Point Code         Conditional   *2
      Subsystem Number            Conditional   *3
      Network Appearance          Conditional   *4
      Diagnostic Info             Conditional   *5

  Note 1: When the Error Code is "Invalid Routing Context," the Routing
          Context parameter MUST contain the invalid routing context
          value(s).

  Note 2: When the Error Code is "Destination Status Unknown" or
          "Subsystem Status Unknown," the Affected Point Code parameter
          MUST contain the point codes for which status is unknown or
          unauthorized.

  Note 3: When the Error Code is "Subsystem Status Unknown," the
          Subsystem Number parameter MUST contain the subsystem for
          which status is unknown or unauthorized.

  Note 4: When the Error Code is "Invalid Network Appearance," the
          Network Appearance parameter MUST contains the invalid network
          appearance value.

  Note 5: The Diagnostic Info parameter SHOULD contain the first 40
          bytes of the message that caused the ERR message to be sent.

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3.8.2.  Notify (NTFY)

  The Notify message is used to provide an autonomous indication of TUA
  events at an SG or IPSP to an ASP.

  The NTFY message is formatted as follows:

     0                     1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x000D          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                           Status                              |
    +-------------------------------+-------------------------------+
    |         Tag = 0x0011          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                        ASP Identifier                         |
    +-------------------------------+-------------------------------
    |         Tag = 0x0006          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                       Routing Context                         /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0004          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                          Info String                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The NTFY message can contain the following parameters:

      Parameters
      ---------------------------------------------
      Status                      Mandatory
      ASP Identifier              Conditional   *1
      Routing Context             Conditional   *2
      Info String                 Optional

  Note 1: ASP Identifier MUST be used where the IPSP/SGP cannot identify
          the ASP by pre-configured address/port number information
          (e.g, where an ASP is resident on a Host using dynamic
          address/port number assignment) and the Status parameter is
          set to "Alternate ASP Active" or "ASP Failure".

  Note 2: When an ASP is registered or configured for multiple AS with
          an SG, to identify the Application Server, the Routing Context
          associated with the AS whose state is being notified MUST be
          placed in the NTFY message when the Status parameter is set to
          "AS_State_Change".

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3.9.  Routing Key Management (RKM) Messages

  Routing Key Management (RKM) messages are used to manage the Routing
  Keys that are used by an SG to direct traffic toward an Application
  Server.

3.9.1.  Registration Request (REG REQ)

  The Registration Request (REG REQ) message is sent by an ASP to
  indicate to a remote TUA peer that it wishes to register one or more
  given Routing Keys with the remote peer.  Typically, an ASP would send
  this message to an SGP, and expects to receive a REG RSP message in
  return with an associated Routing Context value.

  The REG REQ message is formatted as follows:

     0                     1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x041E          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                          Routing Key 1                        /
    \                                                               \
    +-------------------------------+-------------------------------+
    \                                                               \
    /                              ...                              /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x041E          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                          Routing Key n                        /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The REG REQ message can contain the following parameters:

      Parameters
      -------------------------------------------
      Routing Key                 Mandatory   *1

  Note 1: One or more Routing Key parameters MAY be included in a single
          REG REQ message.  Whereas it is OPTIONAL for an implementation
          to be able to generate a REG REQ message with more than one
          Routing Key parameter, it is REQUIRED that the implementation
          be able to receive multiple Routing Key parameters in a single
          REG REQ message.

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3.9.2.  Registration Response (REG RSP)

  The Registration Response (REG RSP) message is sent by an SG to an ASP
  to indicate the result of a previous REG REQ from an ASP.  When
  successful, the REG RSP message contains the Routing Context assigned
  to the one or more Routing Keys that were presented in the REG REQ
  message.

  The REG RSP message is formatted as follows:

     0                     1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x041F          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                     Registration Result 1                     /
    \                                                               \
    +-------------------------------+-------------------------------+
    \                                                               \
    /                              ...                              /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x041F          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                     Registration Result n                     /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The REG RSP message can contain the following parameters:

      Parameters
      -------------------------------------------
      Registration Result         Mandatory   *1

  Note 1: REG RSP message.  Whereas it is OPTIONAL for an implementation
          to be able to generate a REG RSP message with more than one
          Routing Key parameter, it is REQUIRED that the implementation
          be able to receive multiple Routing Key parameters in a single
          REG RSP message.

3.9.3.  Deregistration Request (DEREG REQ)

  The Deregistration Request (DEREG REQ) message is sent by an ASP to
  indicate to a remote TUA peer that it wishes to deregister a given
  Routing Key as identified by the given Routing Context.  Typically, an
  ASP would send this message to an SGP, and expects to receive a DEREG
  RSP message in return with the associated Routing Context value.

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  The DEREG REQ message is formatted as follows:

     0                     1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0006          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Routing Context                        /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The DEREG REQ message contains the following parameters:

      Parameters
      -------------------------------------------
      Routing Context             Mandatory   *1

  Note 1: One or more Routing Context values MAY be included in the
          Routing Context parameter.  Whereas it is OPTIONAL for an
          implementation to be able to generate a DEREG REQ message with
          multiple Routing Context values in the Routing Context
          parameter, it is REQUIRED that an implementation be able to
          receive multiple Routing Context values in the Routing Context
          parameter of the DEREG REQ message.

3.9.4.  Deregistration Response (DEREG RSP)

  The Deregistration Response (DEREG RSP) message is used as a response
  to the DEREG REQ message from a remote TUA peer.

  The DEREG REQ message is formatted as follows:

     0                     1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0420          |            Length = 12        |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                   Deregistration Result 1                     |
    +-------------------------------+-------------------------------+
    \                                                               \
    /                              ...                              /
    \                                                               \
    +-------------------------------+-------------------------------+
    |         Tag = 0x0420          |            Length = 12        |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                   Deregistration Result n                     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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  The DEREG REQ message contains the following parameters:

      Parameters
      -------------------------------------------
      Deregistration Result       Mandatory   *1

  Note 1: One or more Deregistration Result parameters MAY be included
          in one DEREG RSP message.  Whereas it is OPTIONAL for an
          implementation to be able to generate a DEREG RSP message with
          multiple Deregistration Result parameters, it is REQUIRED that
          an implementation be able to receive multiple Deregistration
          Result parameters in a single DEREG RSP message.

3.10.  Common Parameters

  These TLV parameters are common across the different adaptation
  layers.

  Parameter Name       Parameter ID   Section
  --------------------------------------------
  Reserved                0x0000         -
  Not used in TUA         0x0001         -
  Not used in TUA         0x0002         -
  Not used in TUA         0x0003         -
  Info String             0x0004      3.10.1
  Not used in TUA         0x0005         -
  Routing Context         0x0006      3.10.2
  Diagnostic Info         0x0007      3.10.3
  Not used in TUA         0x0008         -
  Heartbeat Data          0x0009      3.10.4
  Not used in TUA         0x000A         -
  Traffic Mode Type       0x000B      3.10.5
  Error Code              0x000C      3.10.6
  Status                  0x000D      3.10.7
  Not used in TUA         0x000E         -
  Not used in TUA         0x000F         -
  Not used in TUA         0x0010         -
  ASP Identifier          0x0011      3.10.8
  Affected Point Code     0x0012      3.10.9
  Correlation Id          0x0013      3.10.12

3.10.1.  Info String

  The Info String parameter is optionally included in all MGMT, ASPSM
  and ASPTM messages to provide additional debugging or diagnostic
  information.

  The Info String parameter is formatted as follows:

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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0004          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                          Info String                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Info String parameter contains the following fields:

  Info String field: variable (ASCII string)

    The Info String field can carry any meaningful 8-bit ASCII character
    string along with the message.  Length of the Info String field is
    from 0 to 255 characters.  No procedures are presently identified
    for its use but implementations may use the Info String for
    debugging purposes.

3.10.2.  Routing Context

  The Routing Context parameter is included in all TUA SSNM, DH and CH
  messages as well as in MGMT, ASPTM, ASPSM that reference one or more
  Application Servers.  The Routing Context parameter is used to
  uniquely identify an Application Server and Routing Key within an
  association between an SGP and ASP.

  The Routing Context parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0006          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                      Routing Context(s)                       /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Routing Context parameter can contain the following fields:

  Routing Context field: list of 32-bit (unsigned integer)

    The Routing Context field contains (a list of) 32-bit unsigned
    integers indexing the Application Server traffic that the sending
    ASP is configured or registered to receive.  There is 1:1
    relationship between a Routing Context value, an SG Routing Key and
    an Application Server [5].

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3.10.3.  Diagnostic Information

  The Diagnostic Info parameter is used in the MGMT Error (ERR) message
  to provide additional information concerning the message that
  generated an Error message reply.  The Diagnostic Info parameter
  SHOULD contain the first 40 bytes of the message that generated the
  error.

  The Diagnostic Info parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0007          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                         Diagnostic Info                       /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Diagnostic Info parameter contains the following fields:

  Diagnostic Info field: variable length (bytes)

    The Diagnostic Info field can contain any information germane to the
    error condition, to assist in the identification of the error
    condition.  The Diagnostic Info SHOULD be the first 40 bytes of the
    offending message.

3.10.4.  Heartbeat Data

  The Heartbeat Data parameter is used in the BEAT and BEAT-Ack messages
  and contains whatever information the sender of the BEAT message
  chooses to include.  Some uses for the Heartbeat Data parameter are
  described in Section 4.

  The Heartbeat Data parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0009          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                         Heartbeat Data                        /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Heartbeat Data parameter contains the following fields:

  Heartbeat Data field: variable length (opaque)

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    The sending node defines the Heartbeat Data field contents.  It may
    include a Heartbeat Sequence Number or Time-stamp, or other
    implementation specific details.  The receiver of a Heartbeat
    message does not process this field as it is only of significance to
    the sender.  The receiver MUST echo the content of the Heartbeat
    Data in a BEAT-Ack message.  The data field can be used to store
    information in the heartbeat message useful to the sending node
    (e.g. the data field can contain a time stamp, a sequence number,
    etc.).

3.10.5.  Traffic Mode Type

  The Traffic Mode Type parameter indicates the fail-over and traffic
  distribution algorithm and procedures that will be used for an
  Application Server Process serving an Application Server.  Each
  Application Server has associated with it only one Traffic Mode Type.

  The Traffic Mode Type parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x000B          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                       Traffic Mode Type                       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Traffic Mode Type parameter contains the following fields:

  Traffic Mode Type field: 32-bits (unsigned integer)

    The Traffic Mode Type field identifies the traffic mode of operation
    of an ASP within an AS.  The valid values for the Traffic Mode Type
    field are as follows:

        1   Override
        2   Loadshare
        3   Broadcast

    Within a Routing Context, Override, Load-share Types and Broadcast
    cannot be mixed.  The Override value indicates that the ASP is
    operating in Override mode, and that when the ASP becomes active for
    the Application Server, it will take over all traffic for the AS
    (i.e, primary/back-up operation), overriding any currently active
    ASP in the AS.  In Load-share mode, when the ASP becomes active for
    the AS, the ASP will share in the traffic distribution with any
    other active ASPs.  In Broadcast mode, when the ASP becomes active
    for the AS, the ASP will receive the same traffic as any other
    active APSs.

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3.10.6.  Error Code

  The Error Code parameter is used in the Error (ERR) message to
  indicate the reason that the ERR message was generated and, along with
  the other parameters in the Error message, help to locate the problem
  that generated the error condition.

  The Error Code parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x000C          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                          Error Code                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Error Code parameter contains the following fields:

  Error Code field: 32-bit (unsigned integer)

    The Error Code field indicates the reason for the Error Message.
    The Error Code field value can be one of the following values:

         1   Invalid Version
         3   Unsupported Message Class
         4   Unsupported Message Type
         5   Unsupported Traffic Handling Mode
         6   Unexpected Message
         7   Protocol Error
         9   Invalid Stream Identifier
        13   Refused - Management Blocking
        14   ASP Identifier Required
        15   Invalid ASP Identifier
        17   Invalid Parameter Value
        18   Parameter Field Error
        19   Unexpected Parameter
        20   Destination Status Unknown
        21   Invalid Network Appearance
        22   No configured AS for ASP
        23   Invalid Routing Context
        24   Subsystem Status Unknown

  The "Invalid Version" error is sent if a message was received with an
  invalid or unsupported version.  The Error message contains the
  supported version in the Common header.  The Error message could
  optionally provide the supported version in the Diagnostic parameter.

  The "Unsupported Message Class" error is sent if a message with an
  unexpected or unsupported Message Class is received.

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  The "Unsupported Message Type" error is sent if a message with an
  unexpected or unsupported Message Type is received.

  The "Unsupported Traffic Handling Mode" error is sent by a SGP if an
  ASP sends an ASP Active message with an unsupported Traffic Mode Type
  or a Traffic Mode Type that is inconsistent with the presently
  configured mode for the Application Server.  An example would be a
  case in which the SGP did not support load-sharing.

  The "Unexpected Message" error MAY be sent if a defined and recognized
  message is received that is not expected in the current state (in some
  cases the ASP may optionally silently discard the message and not send
  an Error message).  For example, silent discard is used by an ASP if
  it received a DATA message from an SGP while it was in the ASP-
  INACTIVE state.  If the Unexpected message contained Routing
  Context(s), the Routing Context(s) SHOULD be included in the Error
  message.

  The "Protocol Error" error is sent for any protocol anomaly (i.e.,
  reception of a parameter that is syntactically correct but unexpected
  in the current situation.

  The "Invalid Stream Identifier" error is sent if a message is received
  on an unexpected SCTP stream (e.g, a Management message was received
  on a stream other than "0", or a Data message was received on stream
  "0").

  The "Refused - Management Blocking" error is sent when an ASP Up or
  ASP Active message is received and the request is refused for
  management reasons (e.g, management lockout").  If this error is in
  response to an ASP Active message, the Routing Context(s) in the ASP
  Active message SHOULD be included in the Error message.

  The "ASP Identifier Required" is sent by a SGP in response to an ASP
  Up message which does not contain an ASP Identifier parameter when the
  SGP requires one.  The ASP SHOULD resend the ASP Up message with an
  ASP Identifier.

  The "Invalid ASP Identifier" is send by a SGP in response to an ASP Up
  message with an invalid (i.e., non-unique) ASP Identifier.

  The "Invalid Parameter Value" error is sent if a message is received
  with an invalid parameter value (e.g, a DUPU message was received with
  a Mask value other than "0").

  The "Parameter Field Error" would be sent if a message is received
  with a parameter having a wrong length field.

  The "Unexpected Parameter" error would be sent if a message contains
  an invalid parameter.

  The "Destination Status Unknown" Error MAY be sent if a DAUD is
  received at an SG inquiring of the availability or congestion status
  of a destination, and the SG does not wish to provide the status (e.g,

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  the sender is not authorized to know the status).  For this error, the
  invalid or unauthorized Point Code(s) MUST be included along with any
  Network Appearance or Routing Context associated with the Point
  Code(s) from the DAUD message.

  The "Invalid Network Appearance" error is sent by a SGP if an ASP
  sends a message with an invalid (unconfigured) Network Appearance
  value.  For this error, the invalid (unconfigured) Network Appearance
  MUST be included in the Network Appearance parameter in the Error
  message.

  The "No Configured AS for ASP" error is sent if a message is received
  from a peer without a Routing Context parameter and it is not known by
  configuration data which Application Servers are referenced.

  The "Invalid Routing Context" error is sent if a message is received
  from a peer with an invalid (unconfigured) Routing Context value, or
  if a message is received from a peer without a Routing Context
  parameter and it is not known by configuration data which Application
  Servers are referenced.  For this error, the invalid Routing
  Context(s) MUST be included in the Error message.

  The "Subsystem Status Unknown" Error MAY be sent if a DAUD is received
  at an SG inquiring of the availability or congestion status of a
  subsystem, and the SG does not wish to provide the status (e.g, the
  sender is not authorized to know the status).  For this error, the
  invalid or unauthorized Point Code and Subsystem Number MUST be
  included along with any Network Appearance or Routing Context
  associated with the Point Code and Subsystem Number from the DAUD
  message.

3.10.7.  Status

  The Status parameter identifies the type of the status that is being
  notified in a Notify (NTFY) message and the Status ID.

  The Status parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x000D          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |         Status Type           |            Status ID          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Status parameter contains the following fields:

  Status Type field: 16-bits (unsigned integer)

    The valid values for Status Type field are as follows:

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        1   Application Server state change (AS_State_Change)
        2   Other

  Status ID field: 16-bits (unsigned integer)

    The Status ID parameter contains more detailed information for the
    notification, based on the value of the Status Type.

    (1)   If the Status Type is "AS_State_Change", then the Status ID
          values are as follows:

              1   reserved
              2   Application Server Inactive (AS-Inactive)
              3   Application Server Active (AS-Active)
              4   Application Server Pending (AS-Pending)

          These notifications are sent from an SGP to an ASP upon a
          change in status of a particular Application Server.  The
          value reflects the new state of the Application Server.

    (2)   If the Status Type is "Other", then the following Status
          Information values are defined:

              1   Insufficient ASP resources active in AS
              2   Alternate ASP Active
              3   ASP failure

          These notifications are not based on the SGP reporting the
          state change of an ASP or AS.  In the Insufficient ASP
          Resources case, the SGP is indicating to an "Inactive" ASP(s)
          in the AS that another ASP is required to handle the load of
          the AS (Load-sharing mode or Broadcast mode).  For the
          Alternate ASP Active case, an ASP is informed when an
          alternate ASP transitions to the ASP-Active state in Override
          mode.

3.10.8.  ASP Identifier

  The ASP Identifier parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0011          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                        ASP Identifier                         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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  The ASP Identifier parameter contains the following fields:

  ASP Identifier field: 32-bits (unsigned integer)

    The ASP Identifier field contains a unique value that is locally
    significant among the ASPs that support an AS.  The SGP should save
    the ASP Identifier to be used, if necessary, with the Notify message
    (see Section 3.7.2).

  The optional ASP Identifier parameter would contain a unique value
  that is locally significant among the ASPs that support an AS.  The
  SGP should save the ASP Identifier to be used, if necessary, with the
  Notify message (see Section 3.3.3.2).

3.10.9.  Affected Point Code

  The Affected Point Code parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0012          |            Length             |
    +- - - - - - - -+- - - - - - - -+- - - - - - - - - - - - - - - -+
    |     Mask      |             Affected Point Code 1             |
    +- - - - - - - -+- - - - - - - - - - - - - - - - - - - - - - - -+
    \                                                               \
    /                              ...                              /
    \                                                               \
    +- - - - - - - -+- - - - - - - - - - - - - - - - - - - - - - - -+
    |     Mask      |             Affected Point Code n             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Affected Point Code parameter contains the following fields:

  Affected Destination Point Code field: n x 32-bits

    The Affected Point Code parameter contains a list of one or more
    Affected Destination Point Code fields.  It is OPTIONAL to generate
    an Affected Point Code parameter with more than one Affected
    Destination Point Code field, but it is REQUIRED to accept it.

  Each Affected Destination Point Code field in the list contains the
  following fields:

  Affected Point Code field: 24-bits (unsigned integer)

    Each Affected Point Code field is a three-octet field to allow for
    up to 24-bit binary formatted SS7 Point Codes.  Affected Point Codes
    that are less than 24-bits are padded on the left to the 24-bit
    boundary.  The following examples show ANSI and ITU-T point codes:

    ANSI 24-bit Point Code:

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       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Mask      |    Network    |    Cluster    |     Member    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                      |MSB-----------------------------------------LSB|

    ITU-T 14-bit Point Code:

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Mask      |0 0 0 0 0 0 0 0 0 0|Zone |     Region    | SP  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                          |MSB---------------------LSB|

  Mask field: 8-bits (unsigned integer)

    The Mask parameter can be used to identify a contiguous range of
    Affected Point Codes, independent of the point code format.
    Identifying a contiguous range of Affected Point Codes may be useful
    when a management event simultaneously affects the status of a
    series of destinations at an SG.

    The Mask parameter is an integer representing a bit mask that can be
    applied to the related Affected PC field.  The bit mask identifies
    how many bits of the Affected PC field are significant and which are
    effectively "wild-carded".  For example, a mask of "8" indicates
    that the last eight bits of the PC is "wild-carded".  For an ANSI
    24-bit Affected PC, this is equivalent to signalling that all PCs in
    an ANSI Cluster are unavailable.  A mask of "3" indicates that the
    last 3 bits of the PC is "wild-carded".  For a 14-bit ITU Affected
    PC, this is equivalent to signalling that an ITU Region is
    unavailable.

    A Mask value equal (or greater than) the number of bits in the Point
    Code indicates that the entire network access is affected: this is
    used to indicate network isolation to the ASP.

3.10.10.  Correlation Id

  The Correlation Id parameter is used to tag messages sent to an ASP in
  a Broadcast group as well as during fail-over.

  The Correlation Id parameter is formatted as follows:

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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0013          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                         Correlation Id                        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Correlation Id parameter can contain the following fields:

  Correlation Id field: 32-bits (unsigned integer)

    The Correlation Id field contains a Correlation Id.  The Correlation
    Id is a 32-bit identifier that is attached to the TUA Message Header
    to indicate to a newly entering ASP in a Broadcast AS where in the
    traffic flow of TUA messages the ASP is joining.  It is attached to
    the TUA Message Header of the first DH or CH message sent to an ASP
    by an SG after sending an ASP Active Ack or otherwise starting
    traffic to an ASP.  The Correlation Id is only significant within a
    Routing Context [6].

3.11.  TUA-Specific parameters

  These TLV parameters are specific to the TUA protocol.

  Parameters used in DH Messages
  --------------------------------------------------
  Parameter Name            Parameter ID   Section
  --------------------------------------------------
  Dialogue Id                  0x0401     3.11.1.1
  Dialogue Flags               0x0402     3.11.1.2
  Quality of Service           0x0403     3.11.1.3
  Destination Address          0x0404     3.11.1.4
  Originating Address          0x0405     3.11.1.5
  Application Context Name     0x0406     3.11.1.6
  User Information             0x0407     3.11.1.7
  Security Context             0x0408     3.11.1.8
  Confidentiality              0x0409     3.11.1.9
  Termination                  0x040A     3.11.1.10
  Abort Cause                  0x040B     3.11.1.11
  Report Cause                 0x040C     3.11.1.12
  Abort Reason                 0x040D     3.11.1.13
  Components                   0x040E     3.11.1.14
  Component                    0x040F     3.11.1.15
  Transaction Id               0x0410     3.11.1.16
  --------------------------------------------------

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  Parameters used in CH Messages
  ----------------------------------------
  Parameter Name   Parameter ID  Section
  ----------------------------------------
  Invoke Id           0x0411     3.11.2.1
  Linked Id           0x0412     3.11.2.2
  Component Flags     0x0413     3.11.2.3
  Operation           0x0414     3.11.2.4
  Parameters          0x0415     3.11.2.5
  Error               0x0416     3.11.2.6
  Problem Code        0x0417     3.11.2.7
  Timeout             0x0418     3.11.2.8
  ----------------------------------------

  Other Parameters
  ----------------------------------------------------------
  Parameter Name                    Parameter ID   Section
  ----------------------------------------------------------
  Subsystem Number                     0x0419     3.11.3.1
  Subsystem Multiplicity Indicator     0x041A     3.11.3.2
  Congestion Level                     0x041B     3.11.3.3
  User/Cause                           0x041C     3.11.3.4
  Network Appearance                   0x041D     3.11.3.5
  Routing Key                          0x041E     3.11.3.6
  Registration Result                  0x041F     3.11.3.7
  Deregistration Result                0x0420     3.11.3.8
  Address Range                        0x0421     3.11.3.9
  Destination Transaction Id           0x0422     3.11.3.10
  Originating Transaction Id           0x0423     3.11.3.11
  Transaction Id Range                 0x0424     3.11.3.12
  Global Title                         0x0425     3.11.3.13
  Point Code                           0x0426     3.11.3.14

3.11.1.  Parameters used in DH Messages

3.11.1.1.  Dialogue Id

  The Dialogue Id parameter is used in the TUA Message Header to
  identify the dialogue within the Application Server indicated by the
  Routing Context (also in the TUA Message Header).

  The Dialogue Id parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0401          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                          Dialogue Id                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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  The Dialogue Id parameter contains the following fields:

  Dialogue Id field: 32-bits (unsigned integer)

    The Dialogue Id field contains an identifier that is used both at
    the SG and the ASP to identify a dialogue within an Application
    Server.  The Dialogue Id value must be unique within the scope of a
    given Application Server and Routing Context.

    For a given AS and Routing Context, either the SG or the ASP is
    responsible for assigning Dialogue Ids, but not both.

3.11.1.2.  Dialogue Flags

  The Dialogue Flags parameter is used in the DH Message Header and is
  used to indicate whether components are present (when the message is
  sent from SG to ASP) and whether permission is granted for the
  receiving TC-User to terminate the dialogue.

  The Dialogue Flags parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0402          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                         Dialogue Flags                        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Dialogue Flags parameter contains the following fields:

  Dialogue Flags field: 32-bits (bit field)

    The Dialogue Flags field contains flag bits used in to indicate
    additional characteristics of the DH message.  The Dialogue Flags
    field is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        reserved                         |C|P| |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

    Bits 0-28: Reserved (coded zero)

      Reserved bits are reserved for later IETF extensions and are coded
      zero.

    Bit 29: Components Present

      The Components Present bit is set in the indication (i.e, sent
      from SG to ASP) forms of Dialogue Handling (DH) messages to

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      indicate that Component Handling (CH) messages will follow
      containing the components associated with the Dialogue Handing
      message.

    Bit 20: Permission

      The Permission bit is cleared in Dialogue Handling (DH) messages
      to indicate that the remote TC-User is not permitted to end the
      dialogue.

    Bit 31: Reserved (coded zero)

      Reserved bits are reserved for later IETF extensions and are coded
      zero.

3.11.1.3.  Quality of Service

  The Quality of Service parameter contains the QoS parameters for the
  underlying SCCP Network Service.

  The Quality of Service parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0403          |            Length = 8         |
    +- - - - - - - -+- - - - - - - -+- - - - - - - -+-+- - -+- - - -+
    | Msg Priority  |  Importance   |  Seq Control  |R|  -  | P Cls |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Quality of Service parameter contains the following fields:

  Protocol Class field: 4-bits (unsigned integer)

    The Protocol Class field indicates the SCCP Protocol Class requested
    by the TC-User for the current Dialogue Handling message.  Valid
    values for the Protocol Class field are as follows:

        0   SCCP Protocol Class 0   TCAP Operation Class 4
        1   SCCP Protocol Class 1   TCAP Operation Class 1, 2, and 3
        2   SCCP Protocol Class 2   TCAP Operation Class 1, 2, and 3
        3   SCCP Protocol Class 3   TCAP Operation Class 1, 2, and 3

  Spare field: 3-bits (coded zero)

    Spare bits are coded zero.

  Return Option field: 1-bit (boolean)

    Specifies whether the SCCP "return message on error" is requested
    when the Protocol Class field is set to SCCP Protocol Class 0 or 1.

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    When the Protocol Class field is set to SCCP Protocol Class 2 or 3,
    this field MAY be ignored by the SG.  The Return Option field has
    the following values:

        0   No "Return On Error" option requested.
        1   "Return On Error" option requested.

  Sequence Control field: 8-bits (unsigned integer)

    When the Protocol Class field is other than SCCP Protocol Class 0,
    the Sequence Control field provides a sequence control parameter
    which is used by the underlying SS7 SCCP and MTP layer at the SG to
    generate an SLS value.  When the Protocol Class field is set to
    Protocol Class 0, this field SHOULD be coded to zero and MUST be
    ignored by the SG.

  Importance field: 8-bits (unsigned integer)

    The Importance field contains the SCCP Importance level requested by
    the TC-User.  Where the underlying SCCP transport at an SG does not
    support SCCP flow control [Q.714], this field SHOULD be coded to
    zero and MUST be ignored by the SG [7].  Valid values for the
    Importance field are as follows:

        0   SCCP Importance Level 0 or Unspecified
        1   SCCP Importance Level 1
        2   SCCP Importance Level 2
        3   SCCP Importance Level 3
        4   SCCP Importance Level 4
        5   SCCP Importance Level 5
        6   SCCP Importance Level 6
        7   SCCP Importance Level 7

  Message Priority field: 8-bits (unsigned integer)

    The Message Priority field contains the MTP Message Priority
    requested when the underlying SS7 transport at an SG supports
    multiple congestion levels [Q.704].  When the underlying transport
    does not support multiplex congestion levels or states, this field
    SHOULD be coded to zero and MUST be ignored by the SG [8].  Valid
    values for the Message Priority field are as follows:

          0   Message Priority 0 or Unspecified
          1   Message Priority 1
          2   Message Priority 2
          3   Message Priority 3

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3.11.1.4.  Destination Address

  The Destination Address parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0404          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                      Address parameter(s)                     /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Destination Address parameter contains the following fields:

  Address field: variable length (address parameter list)

    The Address field contains a list of one or more address parameters.
    At least one address parameter MUST be present in the Address field.
    The Address field can contain the following parameters:

        Parameters
        ---------------------------------------------
        Point Code                  Conditional   *1
        Subsystem Number            Conditional   *1
        Global Title                Optional

  Note :1 When the Address field contains a Subsystem Number parameter,
          it must also contain a Point Code parameter.

3.11.1.5.  Originating Address

  The Originating Address parameter is formatted as follows:

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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0405          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                      Address parameter(s)                     /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Originating Address parameter contains the following fields:

  Address field: variable length (address parameter list)

    The  Address  field  contains  a  list  of  one  or  more  address
    parameters.  At least one address parameter MUST be present in the
    Address  field.   The  Address  field  can  contain  the following
    parameters:

        Parameters
        ---------------------------------------------
        Point Code                  Conditional   *1
        Subsystem Number            Conditional   *1
        Global Title                Optional

  Note :1 When the Address field contains a Subsystem Number  parameter,
          it must also contain a Point Code parameter.

3.11.1.6.  Application Context Name

  The Application Context Name parameter contains the identifier of the
  application context proposed by the dialogue initiator or by the
  dialogue responder.  An application context is an explicitly
  identified set of application-service-elements, related options and
  any other necessary information for the interworking of application-
  entities on a dialogue.

  For a description of the Application Context Name parameter, see the
  ITU [Q.771] TCAP specifications.

  The Application Context Name parameter is formatted as follows:

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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0406          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                       Application Id Type                     |
    +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
    \                                                               \
    /                      Application Identifier                   /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Application Context Name parameter contains the following fields:

  Application Id Type field: 32-bits (unsigned integer)

    The Application Id Type field indicates the type of Application
    Identifier that is present in the Application Identifier field.
    Valid values for the Application Id Type are as follows:

        0   ASN.1 OBJECT IDENTIFIER
        1   ASN.1 INTEGER

  Application Identifier field: variable length (bytes)

    The Application Identifier contains an identifier of the application
    context that is being proposed by the dialogue initiator or
    responder.  When the Application Type is `0' this field MUST be
    formatted as an OBJECT IDENTIFIER [X.680] representing the proposed
    Application Id.  When the Application Type is `1' this field MUST be
    formatted as 32-bit unsigned integer value representing the proposed
    Application Id.

3.11.1.7.  User Information

  The User Information parameter contains information which can be
  exchanged between TC-Users independently from the Remote Operation
  Service.

  For a description of the User Information parameter, see the ITU
  [Q.771] TCAP specifications.

  The User Information parameter is formatted as follows:

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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0407          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                          User Information                     /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The User Information parameter can contain the following fields:

  User Information field: variable length (bytes)

    The internal format of the User Information field is opaque to TUA
    and to TCAP.  The contents of this field is a string of bytes as
    they were provided to the TUA layer by the TC-User in a TC-BEGIN,
    TC-CONT, or TC-END primitive.

3.11.1.8.  Security Context

  The Security Context parameter contains the identifier of the security
  context proposed by the dialogue initiator or by the dialogue
  responder.

  The Security Context parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0408          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                          Security Type                        |
    +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Security Identifier                    /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Security Context parameter contains the following fields:

  Security Id Type field: 32-bits (unsigned integer)

    The Security Id Type field indicates the type of Security Identifier
    that is present in the Security Identifier field.  Valid values for
    the Security Id Type are as follows:

        0   ASN.1 OBJECT IDENTIFIER
        1   ASN.1 INTEGER

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  Security Identifier field: variable length (bytes)

    The Security Identifier contains an identifier of the application
    context that is being proposed by the dialogue initiator or
    responder.  When the Security Type is `0' this field MUST be
    formatted as an OBJECT IDENTIFIER [X.680] representing the proposed
    Security Id.  When the Security Type is `1' this field MUST be
    formatted as 32-bit unsigned integer value representing the proposed
    Security Id.

3.11.1.9.  Confidentiality

  Confidentiality Identifier is coded context specific (in the context
  of the dialogue portion sequence), constructor.

  The Confidentiality parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0409          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                     Confidentiality Id Type                   |
    +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
    \                                                               \
    /                    Confidentiality Identifier                 /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Confidentiality parameter contains the following fields:

  Confidentiality Id Type field: 32-bits (unsigned integer)

    The Confidentiality Id Type field indicates the type of
    Confidentiality Identifier that is present in the Confidentiality
    Identifier field.  Valid values for the Confidentiality Id Type are
    as follows:

        0   ASN.1 OBJECT IDENTIFIER
        1   ASN.1 INTEGER

  Confidentiality Identifier field: variable length (bytes)

    The Confidentiality Identifier contains an identifier of the
    application context that is being proposed by the dialogue initiator
    or responder.  When the Confidentiality Type is `0,' this field MUST
    be formatted as an OBJECT IDENTIFIER [X.680] representing the
    proposed Confidentiality Id.  When the Confidentiality Type is `1,'
    this field MUST be formatted as 32-bit unsigned integer value
    representing the proposed Confidentiality Id.

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3.11.1.10.  Termination

  The Termination parameter indicates the dialogue termination scenario
  chosen by the TC-User (prearranged or basic).

  The Termination parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x040A          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                          Termination                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Termination parameter contains the following fields:

  Termination field: 32-bit (unsigned integer)

    The Termination field indicates the dialogue termination scenario
    chosen by the TC-User and can have one of the following values:

        0   Prearranged
        1   Basic

3.11.1.11.  Abort Cause

  The Abort Cause parameter is included in the TUAB, TPAB, TUAB and TPAB
  messages and indicates the reason for aborting the transaction or
  dialogue.

  The Abort Cause parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x040B          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                          Abort Cause                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Abort Cause parameter contains the following fields:

  Abort Cause field: 32-bit (unsigned integer)

    The Abort Cause field indicates the reason for aborting the dialogue
    and has a TCAP protocol-variant-specific value.  Example values for
    ITU [Q.773] and ANSI [T1.114] are as follows:

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       |                               |
       | ITU-T Description             | ANSI Description
    ---+-------------------------------+-------------------------------
     0 | unrecognized message type     | -
     1 | unrecognized transaction id   | unrecognized package type
     2 | badly formatted transaction   | incorrect transaction portion
       | portion                       |
     3 | incorrect transaction portion | badly structured transaction
       |                               | portion
     4 | resource limitation           | unassigned responding
       |                               | transaction identifier
     5 | L_RESOURCE_LIMIT              | permission to release problem
     6 | invalid dialogue request      | resource unavailable
     7 | pending expired               | unrecognized dialogue portion
       |                               | identifier
     8 | begin expired                 | badly structured dialogue
       |                               | portion
     9 | inactive expired              | missing dialogue portion
    10 | destination address unknown   | inconsistent dialog portion
    11 | network error                 | -
    12 | unrecognized dialogue         | -
       | identifier                    |
    13 | abnormal dialogue portion     | -
    14 | no common dialogue portion    | -

3.11.1.12.  Report Cause

  The Report Cause parameter indicates the reason for the sending of an
  TNOT message and reflects the SCCP reason that would be used for
  returning a TCAP message.

  The Report Cause parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x040C          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                          Report Cause                         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Report Cause parameter contains the following fields:

  Report Cause field: 32-bit (unsigned integer)

    The Report Cause field indicates the reason that a TC-User message
    could not be delivered and has the following values:

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         0   no translation for an address of such nature
         1   no translation for this specific address
         2   subsystem congestion
         3   subsystem failure
         4   unequipped user
         5   MTP failure
         6   network congestion
         7   SCCP unqualified
         8   error in message transport
         9   error in local processing
        10   destination cannot perform re-assembly
        11   SCCP failure
        12   hop counter violation
        13   segmentation not supported
        14   segmentation failed.

3.11.1.13.  Abort Reason

  The Abort Reason parameter indicates whether a dialogue is aborted
  because the received application context name is not supported and no
  alternative one can be proposed or because of any other user problem.

  The Abort Reason parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x040D          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                         Abort Reason                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Abort Reason parameter contains the following fields:

  Abort Reason field: 32-bits (unsigned integer)

    The Abort Reason field indicates whether the dialogue was aborted
    because the received application context name is not supported and
    no alternative can be proposed or because of any other user problem.
    The valid values for Abort Reason are as follows:

        0   application context not supported
        1   user specific

3.11.1.14.  Components

  The Components parameter is used to attach components directly to a
  TUA Dialogue Handling (DH) message instead of in separate Component
  Handling (CH) massages.

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  The Components parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x040E          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |         Tag = 0x040F          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                          Component #1                         /
    \                                                               \
    +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
    \                              .                                \
    /                               .                               /
    \                              .                                \
    /                                                               /
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |         Tag = 0x040F          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                          Component #n                         /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Components parameter contains the following parameters:

      Parameters
      ---------------------------------------------
      Component                   Conditional   *1

  Note 1: The Components parameter MUST contain at least one Component
          parameter, but may contain more than one Component parameter.

3.11.1.15.  Component

  The Component Type field identifies the type of component (CINV, CRES,
  CCAN, etc.) that is contained within a Component parameter.

  The Component Type parameter is formatted as follows:

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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x040F          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                         Component Type                        |
    +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
    \                                                               \
    /                      Component parameter(s)                   /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Component Type parameter contains the following fields:

  Component Type field: 32-bit (unsigned integer)

    The Component Type field indicates the type of component contained
    in the component parameter.  It can take on the following values:
    (Note that not all values are supported for interworking with all
    TCAP protocol variants.)

        0   Invoke Last
        1   Invoke Not Last
        2   Result Last
        3   Result Not Last
        4   Error
        5   Reject (User)
        6   Reject (Local)
        7   Reject (Remote)
        8   Cancel

  Component field: variable length (TLV parameter list)

    The Component field contains the parameters associated with the
    component.  This field may contains the following components,
    however, the formatting of the Component field MUST be the same as
    for the corresponding TUA message as follows:

        Component Type        CH Msg   Section
        --------------------+------------------
        0   Invoke Last     |
        --------------------+  CINV     3.4.2
        1   Invoke Not Last |
        --------------------+------------------
        2   Result Last     |
        --------------------+  CRES     3.4.3
        3   Result Not Last |
        --------------------+------------------

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        Component Type        CH Msg   Section
        --------------------+------------------
        4   Error           |  CERR     3.4.4
        --------------------+------------------
        5   Reject (User)   |
        --------------------+
        6   Reject (Local)  |  CREJ     3.4.5
        --------------------+
        7   Reject (Remote) |
        --------------------+------------------
        8   Cancel          |  CCAN     3.4.6
        --------------------+------------------

3.11.1.16.  Transaction Id

  The Transaction Id parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0410          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                         Transaction Id                        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Transaction Id parameter contains the following fields:

  Transaction Id field: 32-bits (unsigned integer)

     The Transaction Id field contains the value of the originating or
     terminating transaction identifier.

3.11.2.  Parameters used in CH Messages

3.11.2.1.  Invoke Id

  The Invoke Id parameter identifies an invoke component.  This
  identifier is only significant within the scope of a transaction and
  need only uniquely identify a dialogue within a transaction in a given
  direction (e.g, from SGP to ASP).  The value of the Invoke Id
  parameter is chosen by the TUA peer sending the Invoke.  As both the
  ASP and SGP could be assigning the same values of Invoke Id to
  invocations in each direction, the Invoke Id need only be unique in
  one direction.

  The Invoke Id parameter is formatted as follows:

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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0411          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                           Invoke Id                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Invoke Id parameter contains the following fields:

  Invoke Id field: 32-bit (unsigned integer)

    The Invoke Id field contains the value of the invoke identifier for
    the current component.

3.11.2.2.  Linked Id

  The Linked Id parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0412          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                           Linked Id                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Linked Id parameter contains the following fields:

  Linked Id field: 32-bit (unsigned integer)

    The Linked Id field contains the value of the linked or correlation
    invoke identifier which is related to the current component.

3.11.2.3.  Component Flags

  The Component Flags parameter is used in the CINV and CRES CH messages
  to indicate whether the contained components are segmented and whether
  they represent the last segment in a sequence of component segments.

  The Component Flags parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0413          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                          unused                             |N|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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  The Component Flags parameter contains the following fields:

  Component Flags field: 32-bits

    The Component Flags field is used to convey information about the
    components in a Component Handling (CH) message.  It contains the
    following bit fields:

    Bits 0-30: Unused

      These bits are reserved and are coded to zero.

    Bit 31: Not Last Bit

      The Not Last bit is used to indicate whether the component present
      in the CH message is the last component of a sequence of segmented
      components.  It has the following values:

          0   Last component in a component sequence.
          1   Not the last component in a component sequence.

      To smoothly interwork with TCAP, TUA includes a mechanism whereby
      components can be segmented: the CH message with the "Not Last"
      bit set in the Component Flags field provides for the initial
      segments of a segmented component, whereas the CH message with the
      "Not Last" bit clear in the Component Flags field provides for the
      final (or only) segment in a sequence of component segments
      representing the complete component.  When interworking with TCAP,
      each component segment may be sent in a different TCAP package
      [Q.775].

3.11.2.4.  Operation

  The Operation parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0414          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                         Operation Class                       |
    +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
    |                         Operation Type                        |
    +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
    \                                                               \
    /                         Operation Code                        /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Operation parameter contains the following fields:

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  Operation Class field: 32-bit (unsigned integer)

    The Operation Class field indicates the operational class of the
    invoke in which it appears and has the following values:

        0             not specified
        1   Class 1   both success and failure are reported
        2   Class 2   only failure is reported
        3   Class 3   only success is reported
        4   Class 4   neither success, nor failure is reported

  Operation Type field: 32-bit (unsigned integer)

    The Operation Type field indicates the type of operation code and
    has the following values:

        1   National TCAP Operation   INTEGER
        2   Private TCAP Operation    INTEGER
        3   Local TCAP Operation      INTEGER
        4   Global TCAP Operation     OBJECT IDENTIFIER

  Operation Code field: variable length (based on type)

    The Operation Code field contains an identifier of the requested
    operation.  When the Operation Type is "National," "Private," or
    "Local," this field MUST be formatted as 32-bit unsigned integer
    value representing the requested operation.  When the Operation Type
    is "Global," this field MUST be formatted as an OBJECT IDENTIFIER
    [X.680].  representing the requested operation.  The value of this
    field is TCAP protocol-variant-specific.

3.11.2.5.  Parameters

  The Parameters parameter identifies the parameter set or parameter
  sequence that accompanies an operation invocation or response.

  The Parameters parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0415          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                           Parameters                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Parameters parameter contains the following fields:

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  Parameters field: variable length (bytes)

    The Parameters field contains all of the parameters coded according
    to the coding [X.680] for Parameter Sequences or Parameter Sets per
    the applicable TCAP protocol specification.  For example, ITU
    [Q.773] or ANSI [T1.114].  [9]

3.11.2.6.  Error

  The Error parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0416          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                           Error Type                          |
    +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
    \                                                               \
    /                           Error Code                          /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Error parameter contains the following fields:

  Error Type field: 32-bit (unsigned integer)

    The Error Type field indicates the level (i.e, local or global) at
    which the error was generated.  It has the following values:

        1   National TCAP Error   INTEGER
        2   Private TCAP Error    INTEGER
        3   Local TCAP Error      INTEGER
        4   Global TCAP Error     OBJECT IDENTIFIER

  Error Code field: variable length (based on type)

    The Error Code field contains an identifier of the indicated error.
    When the Error Type is "National," "Private," or "Local," this field
    MUST be formatted as a 32-bit signed integer value representing the
    indicated error.  When the Error Type is "Global," this field MUST
    be formatted as an OBJECT IDENTIFIER [X.680] representing the
    indicated error.  The value of this field is TCAP protocol-variant-
    specific.

3.11.2.7.  Problem Code

  The Problem Code parameters identifies the reason for rejecting a
  component.

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  The Problem Code parameters is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0417          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                          Problem Type                         |
    +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
    |                          Problem Code                         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Problem Code parameters contains the following fields:

  Problem Type field: 32-bit (unsigned integer)

    The Problem Type field indicates the reason for rejecting a
    component and has the following values: (Note that not all problem
    type field values are applicable to all TCAP protocol variants.)

        0   General Problem
        1   Problem with Invoke
        2   Problem with Return Result
        3   Problem with Return Error
        4   Problem with Transaction Portion (deprecated)

  Problem Code field: variable length (signed integer)

    The Problem Code field indicates the specific problem associated
    with the Problem Type.  For more information on problem codes, see
    Q.773 Chapter 4.2.2.6 and ANSI T1.114.3 Chapter 5.16.2.

  Problem Code field: 32-bit (signed integer)

    The Problem Code field indicates the specific problem associated
    with the Problem Type.  This is a TCAP protocol-variant-specific
    value.  Following are some example values for ITU [Q.773] and ANSI
    [T1.114]:

            ITU                         ANSI
  --------------------------------------------------------------------
  General 0 unrecognized component      -
  Problem 1 mis-typed component         unrecognized component type
          2 badly structured component  incorrect component portion
          3 -                           badly structured component
                                        portion
  --------------------------------------------------------------------
  Invoke  0 duplicate invoke id         -
  Problem 1 unrecognized operation      duplicate invocation

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          2 mis-typed parameter         unrecognized operation
          3 resource limitation         incorrect parameter
          4 initiating release          unrecognized correlation id
          5 unrecognized linked id      -
          6 linked response unexpected  -
          7 unexpected linked operation -
  --------------------------------------------------------------------
  Return  0 unrecognized invoke id      -
  Result  1 return result unexpected    unrecognized correlation id
  Problem 2 mis-typed parameter         unexpected return result
          2 -                           incorrect parameter
  --------------------------------------------------------------------
  Return  0 unrecognized invoke id      -
  Error   1 return error unexpected     unexpected return error
  Problem 2 unrecognized error          unrecognized error
          3 unexpected error            unexpected error
          4 mis-typed parameter         incorrect parameter
  --------------------------------------------------------------------
  Trans   1 -                           unrecognized package type
  Portion 2 -                           incorrect transaction portion
  Problem 3 -                           badly structured transaction
                                        portion
  (depr.) 4 -                           unassigned responding
                                        transaction id
          5 -                           permission to release problem
          6 -                           resource unavailable
  --------------------------------------------------------------------

3.11.2.8.  Timeout

  The Timeout parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0418          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                            Timeout                            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Timeout parameter contains the following fields:

  Timeout field: 32-bit (unsigned integer)

    The Timeout field contains the timeout value in seconds that the
    sender will wait before an invocation is canceled.

3.11.3.  Other Parameters

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3.11.3.1.  Subsystem Number

  The Subsystem Number parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0419          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                     Reserved                  |      SSN      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Subsystem Number parameter contains the following fields:

  Reserved field: 24-bits (coded zero)

    Reserved bits are coded zero.

  SSN field: 8-bits (unsigned integer)

    The SSN field contains the SCCP subsystem number [Q.713, T1.112].

3.11.3.2.  Subsystem Multiplicity Indicator

  The Subsystem Multiplicity Indicator is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x041A          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                     Reserved                  |      SMI      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Subsystem Multiplicity Indicator contains the following fields:

  Reserved field: 24-bits (coded zero)

    Reserved bits are coded zero.

  SMI field: 8-bits (unsigned integer)

    The SMI field contains the SCCP subsystem multiplicity indicator.
    Valid values for the SMI field are as follows:

          0    Reserved/Unknown
          1    Solitary
          2    Duplicated
          3    Triplicated

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          4    Quadruplicated
         ...    ...
        255    Unspecified

3.11.3.3.  Congestion Level

  The Congestion Level parameter is used to indicate the MTP network
  congestion level or SCCP restricted importance level and is used in
  the Network Congestion (SCON) message.

  The Congestion Level parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x041B          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                        Congestion Level                       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Congestion Level parameter contains the following fields:

  Congestion Level field: 32-bits (unsigned integer)

    The Congestion Level field contains the level at which congestion
    has occurred.

    When the Congestion Level parameter is included in a SCON message
    that corresponds to an N-PCSTATE request indication primitive, the
    Congestion Level field indicates the MTP congestion level
    experienced by the local or affected signalling point as indicated
    by the Affected Point Code(s) also in the SCON message.  In this
    case, valid values for the Congestion Level field are as follows:

        0   No Congestion or Undefined
        1   Congestion Level 1
        2   Congestion Level 2
        3   Congestion Level 3

    When the Congestion Level parameter is included in a SCON message
    that corresponds to an N-STATE request or indication primitive, the
    Congestion Level field indicates the SCCP restricted importance
    level experienced by the local or affected subsystem as indicated by
    the Affected Point Code and Subsystem Number also in the SCON
    message.  In this case, valid values for the Congestion Level field
    range from 0 to 7, where 0 indicates the least congested and 7
    indicates the most congested subsystem.

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3.11.3.4.  User/Cause

  The User/Cause parameter is used to report the affected user and the
  cause of the unavailability of the user in a DUPU message.

  The User/Cause parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x041C          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |              Cause            |             User              |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The User/Cause parameter contains the following fields:

  Cause field: 16-bits (unsigned integer)

    The Cause field indicates the cause of the unavailability of the
    remote user.  Valid Cause values are as follows:

        0    Unknown
        1    Unequipped Remote User
        2    Inaccessible Remote User

  User field: 16-bits (unsigned integer)

    The User field contains the SI value of the MTP User [Q.704] that is
    being reported unavailable.  For TUA, this is the SI value of the
    SCCP (normally SI = 3).  The TC-User MAY ignore the User field.

3.11.3.5.  Network Appearance

  The Network Appearance parameter is used as a parameter in the
  Registration Request (REG REQ) message to indicate the network context
  in which the remainder of the Routing Key parameters are to be
  interpreted.  The Network Appearance parameter is also used in the
  Error (ERR) message in response to a REG REQ message when a received
  Network Appearance parameter contains an invalid value.

  The Network Appearance parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x041D          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                        Network Appearance                     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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  The Network Appearance parameter can contain the following fields:

  Network Appearance field: 32-bits (unsigned integer)

    The Network Appearance field identifies the SS7 network context for
    the Routing Key.  The Network Appearance value is of local
    significance only, coordinated between the SG and ASP.  Therefore,
    in the case where the ASP is connected to more than one SG, the same
    SS7 Network context may be identified by a different Network
    Appearance value depending upon to which SG the ASP is registering.

    In the Routing Key, the Network Appearance identifies the SS7 Point
    Code and Global Title Transaction Type format used, and the SCCP,
    TCAP and TC-User protocol (type, variant and version) used within
    the specific SS7 network.

3.11.3.6.  Routing Key

  The Routing Key parameter is used in the REG REQ message to list and
  identify the Routing Keys that are being registered.

  The Routing Key parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x041E          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                  Local Routing Key Identifier                 |
    +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
    \                                                               \
    /                        Key parameter(s)                       /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Routing Key parameter can contain the following fields:

  Local Routing Key Identifier field: 32-bits (unsigned integer)

    The Local Routing Key Identifier field is used to uniquely identify
    the registration request.  The identifier value is assigned by the
    ASP and is used to correlate the response in a REG RSP message with
    the original registration request.  The identifier value must remain
    unique until the REG RSP (or ERR) message is received.

  Key field: variable (TLV parameters)

    The key field can contain the following parameters:

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        Parameters
        ----------------------------------------------
        Network Appearance           Conditional   *1
        Traffic Mode Type            Optional
        Originating Address          Optional
        Destination Address          Optional
        Address Range                Optional
        Originating Transaction Id   Optional
        Destination Transaction Id   Optional
        Transaction Id Range         Optional
        Application Context Name     Optional
        User Information             Optional

    Note 1: The Network Appearance parameter MUST be included in the
            Routing Key when the ASP is able to register in multiple SS7
            Network contexts.

3.11.3.7.  Registration Result

  The Registration Result parameter is used to identify and report the
  result of the registration request for each Routing Key that was
  requested registered in a REG REQ message.

  The Registration Result parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x041F          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                  Local Routing Key Identifier                 |
    +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
    |                       Registration Status                     |
    +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
    |                         Routing Context                       |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Registration Result parameter can contain the following fields:

  Local Routing Key Identifier field: 32-bit (unsigned integer)

    The Local Routing Key Identifier field contains the same value as
    found in the matching Routing Key parameter in the REG REQ message.

  Registration Status field: 32-bits (unsigned integer)

    The Registration Status field indicates the success or the reason
    for failure of a registration request.

    Its values may be:

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         0   Successfully Registered
         1   Error - Unknown
         2   Error - Invalid Destination Address
         3   Error - Invalid Network Appearance
         4   Error - Invalid Routing Key
         5   Error - Permission Denied
         6   Error - Cannot Support Unique Routing
         7   Error - Routing Key not Currently Provisioned
         8   Error - Insufficient Resources
         9   Error - Unsupported RK parameter field
        10   Error - Unsupported/Invalid Traffic Mode Type

  Routing Context field: 32-bits (unsigned integer)

    The Routing Context field contains the Routing Context value for the
    associated Routing Key if the registration was successful.  It is
    set to "0" if the registration was not successful.

3.11.3.8.  Deregistration Result

  The Deregistration Result parameter is used to identify and report the
  result of the deregistration request for each Routing Context that was
  requested deregistered and a DEREG REQ message.

  The Deregistration Result parameter contains the deregistration status
  for a single Routing Context in a DEREG REQ message.  The number of
  results in a DEREG RSP message MAY by anywhere from one to the total
  number of Routing Context values found in the corresponding REG REQ
  message.  Where multiple DEREG RSP messages are used in reply to a
  single DEREG REQ message, a specific result SHOULD be in only one
  DEREG RSP message.

  The Deregistration Result parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0420          |            Length = 12        |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                         Routing Context                       |
    +- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -+
    |                      Deregistration Status                    |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Deregistration Result parameter can contain the following fields:

  Routing Context field: 32-bits (unsigned integer)

    The Routing Context field contains the Routing Context value of the
    matching Routing Key to deregister, as found in the DEREG REQ
    message.

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  Deregistration Status field: 32-bits (unsigned integer)

    The Deregistration Status field indicates the success or the reason
    for failure of the deregistration.

    Its values may be:

        0   Successfully Deregistered
        1   Error - Unknown
        2   Error - Invalid Routing Context
        3   Error - Permission Denied
        4   Error - Not Registered
        5   Error - ASP Currently Active for Routing Context

3.11.3.9.  Address Range

  The Address Range parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0421          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                       Address Parameter(s)                    /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Address Range parameter can contain the following fields:

  Address field: variable (TLV parameters)

    The Address field can contain the following parameters:

        Parameters
        ---------------------------------------------
        Originating Address         Conditional   *1
        Destination Address         Conditional   *1

    Note 1: The Address field must contain pairs of Originating
            Addresses or Destination Addresses and MUST contain one and
            only one pair of addresses; but, MUST NOT mix Originating
            Addresses with Destination Addresses in the same Address
            field.

3.11.3.10.  Destination Transaction Id

  The Destination Transaction Id parameter is formatted as follows:

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     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0422          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                    Destination Transaction Id                 |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Destination Transaction Id parameter can contain the following
  fields:

  Destination Transaction Id field: 32-bits (unsigned integer)

    The Destination Transaction Id field contains the Destination
    Transaction Identifier associated with the dialogue.

3.11.3.11.  Originating Transaction Id

  The Originating Transaction Id parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0423          |            Length = 8         |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    |                    Originating Transaction Id                 |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Originating Transaction Id parameter can contain the following
  fields:

  Originating Transaction Id field: 32-bits (unsigned integer)

    The Originating Transaction Id field contains the Originating
    Transaction Identifier associated with the dialogue.

3.11.3.12.  Transaction Id Range

  The Transaction Id Range parameter is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0424          |            Length             |
    +- - - - - - - - - - - - - - - -+- - - - - - - - - - - - - - - -+
    \                                                               \
    /                   Transaction Id Parameter(s)                 /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

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  The Transaction Id Range parameter can contains the following fields:

  Transaction Id field: list of 32-bit (unsigned integer)

    The Transaction Id field can contain the following parameters:

        Parameters
        -------------------------------------------
        Originating Transaction Id   Optional   *1
        Destination Transaction Id   Optional   *1

    Note 1: The Transaction Id field must contain pairs of Originating
            Transaction Ids or Destination Transaction Ids and MUST
            contain one and only one pair of Transaction Id parameters;
            but, MUST NOT mix Originating Transaction Ids with
            Destination Transaction Ids in the same Transaction Id
            field.

3.11.3.13.  Global Title

  The Global Title parameters is formatted as follows:

     0                   1                   2                   3
     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |         Tag = 0x0425          |            Length             |
    +- - - - - - - -+- - - - - - - -+- - - -+- - - -+- - - - - - - -+
    | Num. Digits   |  Trans. Type  | N Plan| E Sch | Nature of Add |
    +- - - - - - - -+- - - - - - - -+- - - -+- - - -+- - - - - - - -+
    \                                                               \
    /                      Global Title Address                     /
    \                                                               \
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

  The Global Title parameters contains the following fields:

  Number of Digits field: 8-bits (unsigned integer)

    The Number of Digits field contains the number of address signals
    that are represented in the Global Title Address field.

  Translation Type field: 8-bits (unsigned integer)

    The Translation Type field contains the translation type to be
    performed on the address information in the Global Title parameter.
    This is a TCAP protocol-variant-specific value.  Example valid
    values for ITU [Q.713] are as follows:

          0      unknown

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          1- 63  international services
        128-254  national network specific

  Numbering Plan field: 4-bits (unsigned integer)

    The Numbering Plan field contains the numbering plan to which the
    address information contained in the Global Title Address field
    belongs.  This is a TCAP protocol-variant-specific value.  Example
    valid values for ITU [Q.713] are as follows:

            0    unknown
            1    ISDN/telephony numbering plan (E.163 and E.164)
            2    generic numbering plan
            3    data numbering plan (X.121)
            4    telex numbering plan (F.69)
            5    maritime mobile numbering plan (E.210, E.211)
            6    land mobile numbering plan (E.212)
            7    ISDN/mobile numbering plan (E.214)
           14    private network or network-specific numbering plan

  Encoding Scheme field: 4-bits (unsigned integer)

    The Encoding Scheme field contains the format for the address
    information contained in the Global Title Address field.  This is a
    TCAP protocol-variant-specific value.  Example valid values for ITU
    [Q.713] are as follows:

           0     unknown
           1     BCD, odd number of digits
           2     BCD, even number of digits
           3     national specific

  Nature of Address field: 8-bits (unsigned integer)

    The Nature of Address field contains an indication of the nature of
    the information represented in the Global Title Address field.  This
    is a TCAP protocol-variant-specific value.  Example valid values for
    ITU [Q.713] are as follows:

           0     unknown
           1     subscriber number
           2     reserved for national use
           3     national significant number
           4     international number

  Global Title Address field: variable length (bytes)

    The Global Title Digits field contains the global title address
    information.  This information is formatted according to the

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    Encoding Scheme, belongs to the Numbering Plan, has the Nature of
    Address, and contains the Number of Digits.  When the encoding
    scheme is BCD, the Global Title Digits field is formatted as
    follows:

     0                   1                   2                   3
     0 1