- 1 - AP IX-127-E 6.3.4 Coding of the call reference For general rules, format and coding of call reference values,  4.3 of Recommendation Q.931 is applicable. For the functional supplementary service control, the dummy call reference is not applicable. 7. Message functional definitions and content This section should be read in conjunction with  3 of Recommendation Q.931. All messages are additional to those defined in that section and the following tables should be interpreted according to the introduction of  3 of Recommendation Q.931. 7.1 Messages for supplementary service control Table 7-1/Q.932 summarizes the messages specific to supplementary service control procedures. TABLE 7-1/Q.932 Messages specific to supplementary service control Reference FACILITY 7.1.1 HOLD 7.1.2 HOLD ACKNOWLEDGE 7.1.3 HOLD REJECT 7.1.4 REGISTER 7.1.5 RETRIEVE 7.1.6 RETRIEVE ACKNOWLEDGE 7.1.7 RETRIEVE REJECT 7.1.8 7.1.1 FACILITY This message may be sent to request or acknowledge a supplementary service. The supplementary service to be invoked, and its associated parameters, are specified in the Facility information element (see Table 7-2/Q.932). For the use of this message, see  6. TABLE 7-2/Q.932 FACILITY message content Message type: FACILITY (3276) - 2 - AP IX-127-E Significance: local (Note 1) Direction: both 旼컴컴컴컴컴컴컴컴컴컴컴쩡컴컴컴컴컴컴컫컴컴컴컴컴컫컴컴컴컴컴쩡컴컴컴컴� 쿔nformation element � Reference � Direction � Type � Length � �=======================�==============�===========�==========�=========� 쿛rotocol discriminator � 4.2/Q.931 � both � M � 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컵컴컴컴컴컴컵컴컴컴컴컴탠컴컴컴컴� 쿎all reference � 4.3/Q.931 � both � M � 2-* � 쳐컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컵컴컴컴컴컴컵컴컴컴컴컴탠컴컴컴컴� 쿘essage type � 4.4/Q.931 � both � M � 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컵컴컴컴컴컴컵컴컴컴컴컴탠컴컴컴컴� 쿑acility � 8.2/Q.932 � both � M � 8-* � 쳐컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컵컴컴컴컴컴컵컴컴컴컴컴탠컴컴컴컴� 쿏isplay � 4.5/Q.931 � n -> u � 0(Note 2)� (Note 3)� 읕컴컴컴컴컴컴컴컴컴컴컴좔컴컴컴컴컴컴컨컴컴컴컴컴컨컴컴컴컴컴좔컴컴컴컴� Note 1 - This message has local significance; however it may carry information of global significance. Note 2 - Included if the network provides information that can be presented to the user. Note 3 - The minimum length is 2 octets. The maximum length is network dependent and is either 34 or 82 octets. 7.1.2 HOLD This message is sent by the network or the user to request the hold function for an existing call (see Table 7-3/Q.932). For the use of this message, see  6. TABLE 7-3/Q.932 HOLD message content Message type: HOLD Significance: local Direction: both 旼컴컴컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴컴컴쩡컴컴컴컴컴컫컴컴컴컴컴컴쩡컴컴컴컴커 � � � � � � � Information element � Reference � Direction � Type � Length � �========================�==============�============�============�==========� � � � � � � � Protocol discriminator � 4.2/Q.931 � both � M � 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴탠컴컴컴컴컴컵컴컴컴컴컴컴탠컴컴컴컴캑 (3276) - 3 - AP IX-127-E � Call reference � 4.3/Q.931 � both � M � 2-* � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴탠컴컴컴컴컴컵컴컴컴컴컴컴탠컴컴컴컴캑 � Message type � 4.4/Q.931 � both � M � 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴탠컴컴컴컴컴컵컴컴컴컴컴컴탠컴컴컴컴캑 � Display � 4.5/Q.931 � n -> u � 0(Note 1) � (Note 2) � 읕컴컴컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴컴컴좔컴컴컴컴컴컨컴컴컴컴컴컴좔컴컴컴컴켸 Note 1 - Included if the network provides information that can be presented to the user. Note 2 - The minimum length is 2 octets. The maximum length is network dependent and is either 34 or 82 octets. 7.1.3 HOLD ACKNOWLEDGE This message is sent by the network or the user to indicate that the hold function has been successfully performed (see Table 7-4/Q.932). For the use of this message, see  6. TABLE 7-4/Q.932 HOLD ACKNOWLEDGE message content Message type: HOLD ACKNOWLEDGE Significance: local Direction: both 旼컴컴컴컴컴컴컴컴컴컴컴컴쩡컴컴컴컴컴컴쩡컴컴컴컴컴쩡컴컴컴컴컴쩡컴컴컴컴커 � � � � � � � Information element � Reference � Direction � Type � Length � �=========================�=============�===========�===========�==========� � Protocol discriminator � 4.2/Q.931 � both � M � 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴캑 � Call reference � 4.3/Q.931 � both � M � 2-* � 쳐컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴캑 � Message type � 4.4/Q.931 � both � M � 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴캑 � Display � 4.5/Q.931 � n -> u � 0(Note 1) � (Note 2) � 읕컴컴컴컴컴컴컴컴컴컴컴컴좔컴컴컴컴컴컴좔컴컴컴컴컴좔컴컴컴컴컴좔컴컴컴컴켸 Note 1 - Included if the network provides information that can be presented to the user. Note 2 - The minimum length is 2 octets. The maximum length is network dependent and is either 34 or 82 octets. 7.1.4 HOLD REJECT This message is sent by the network or the user to indicate the denial of (3276) - 4 - AP IX-127-E a request to hold a call (see Table 7-5/Q.932). For the use of this message, see  6. TABLE 7-5/Q.932 HOLD REJECT message content Message type: HOLD REJECT Significance: local Direction: both 旼컴컴컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴컴쩡컴컴컴컴컴쩡컴컴컴컴컫컴컴컴컴컴� � Information element � Reference � Direction � Type � Length � �========================�============�===========�==========�==========� � Protocol discriminator � 4.2/Q.931 � both � M � 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴컵컴컴컴컴컴� � Call reference � 4.3/Q.931 � both � M � 2-* � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴컵컴컴컴컴컴� � Message type � 4.4/Q.931 � both � M � 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴컵컴컴컴컴컴� � Cause � 4.5/Q.931 � both � M � 4-32 � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴컵컴컴컴컴컴� � Display � 4.5/Q.931 � n -> u � 0(Note 1)� (Note 2)� 읕컴컴컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴컴좔컴컴컴컴컴좔컴컴컴컴컨컴컴컴컴컴� Note 1 - Included if the network provides information that can be presented to the user. Note 2 - The minimum length is 2 octets. The maximum length is network dependent and is either 34 or 82 octets. 7.1.5 REGISTER This message is sent by the user or the network to assign a new call reference for non-call associated transactions (see Table 7-6/Q.932). For the use of this message, see  6. TABLE 7-6/Q.932 REGISTER message content Message type: REGISTER Significance: local (Note 1) Direction: both 旼컴컴컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴컴컫컴컴컴컴컴컴쩡컴컴컴컴컴컫컴컴컴컴컴커 � Information element � Reference � Direction � Type � Length � (3276) - 5 - AP IX-127-E �========================�=============�============�============�===========� � Protocol discriminator � 4.2/Q.931 � both � M � 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컵컴컴컴컴컴컴탠컴컴컴컴컴컵컴컴컴컴컴캑 � Call reference � 4.3/Q.931 � both � M � 2-* � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컵컴컴컴컴컴컴탠컴컴컴컴컴컵컴컴컴컴컴캑 � Message type � 4.4/Q.931 � both � M � 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컵컴컴컴컴컴컴탠컴컴컴컴컴컵컴컴컴컴컴캑 � Facility � 8.2/Q.932 � both � 0(Note 4) � 2-* � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컵컴컴컴컴컴컴탠컴컴컴컴컴컵컴컴컴컴컴캑 � Display � 4.5/Q.931 � n -> u � 0(Note 2) � (Note 3) � 읕컴컴컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴컴컨컴컴컴컴컴컴좔컴컴컴컴컴컨컴컴컴컴컴켸 Note 1 - This message has local significance; however it may carry information of global significance. Note 2 - Included if the network provides information that can be presented to the user. Note 3 - The minimum length is 2 octets. The maximum length is network dependent and is either 34 or 82 octets. Note 4 - Included if the network or the user provides supplementary service information. 7.1.6 RETRIEVE This message is sent by the network or the user to request the retrieval of a held call (see Table 7-7/Q.932). For the use of this message, see  6. TABLE 7-7/Q.932 RETRIEVE message content Message type: RETRIEVE Significance: local Direction: both 旼컴컴컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴컴컴쩡컴컴컴컴컴쩡컴컴컴컴컴쩡컴컴컴컴커 � Information element � Reference � Direction � Type � Length � �========================�==============�===========�===========�==========� � Protocol discriminator � 4.2/Q.931 � both � M � 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴캑 � Call reference � 4.3/Q.931 � both � M � 2-* � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴캑 � Message type � 4.4/Q.931 � both � M � 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴캑 � Channel identification � 4.5/Q.931 � both � 0(Note 1) � 2-* � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴캑 (3276) - 6 - AP IX-127-E � Display � 4.5/Q.931 � n -> u � 0(Note 2) � (Note 3) � 읕컴컴컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴컴컴좔컴컴컴컴컴좔컴컴컴컴컴좔컴컴컴컴켸 Note 1 - If not included, its absence is interpreted as any channel acceptable. Note 2 - Included if the network provides information that can be presented to the user. Note 3 - The minimum length is 2 octets. The maximum length is network dependent and is either 34 or 82 octets. 7.1.7 RETRIEVE ACKNOWLEDGE This message is sent by the network or the user to indicate that the retrieve function has been successfully performed (see Table 7-8/Q.932). For the use of this message, see  6. TABLE 7-8/Q.932 RETRIEVE ACKNOWLEDGE message content Message type: RETRIEVE ACKNOWLEDGE Significance: local Direction: both 旼컴컴컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴컴컴쩡컴컴컴컴컴쩡컴컴컴컴컴쩡컴컴컴컴� � Information element � Reference � Direction � Type 쿗ength � �========================�==============�===========�===========�=========� � Protocol discriminator � 4.2/Q.931 � both � M � 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴� � Call reference � 4.3/Q.931 � both � M � 2-* � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴� � Message type � 4.4/Q.931 � both � M � 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴� � Channel identification � 4.5/Q.931 � both � 0(Note 1) � 2-* � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴컴탠컴컴컴컴� � Display � 4.5/Q.931 � n -> u � 0(Note 2) � (Note 3)� 읕컴컴컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴컴컴좔컴컴컴컴컴좔컴컴컴컴컴좔컴컴컴컴� Note 1 - Mandatory in all cases except when the sender accepts the specific B Channel indicated in the RETRIEVE message. If included, a channel is indicated and specified as exclusive. Note 2 - Included if the network provides information that can be presented to the user. Note 3 - The minimum length is 2 octets. The maximum length is network dependent and is either 34 or 82 octets. (3276) - 7 - AP IX-127-E 7.1.8 RETRIEVE REJECT This message is sent by the network or the user to indicate the inability to perform the requested retrieve function (see Table 7-9/Q.932). For the use of this message, see  6. TABLE 7-9/Q.932 RETRIEVE REJECT message content Message type: RETRIEVE REJECT Significance: local Direction: both 旼컴컴컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴컴컫컴컴컴컴컴컴쩡컴컴컴컴컴컴쩡컴컴컴컴커 � Information element � Reference � Direction � Type � Length � �========================�=============�============�=============�==========� � Protocol discriminator � 4.2/Q.931 � both � M � 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컵컴컴컴컴컴컴탠컴컴컴컴컴컴탠컴컴컴컴캑 � Call reference � 4.3/Q.931 � both � M � 2-* � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컵컴컴컴컴컴컴탠컴컴컴컴컴컴탠컴컴컴컴캑 � Message type � 4.4/Q.931 � both � M � 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컵컴컴컴컴컴컴탠컴컴컴컴컴컴탠컴컴컴컴캑 � Cause � 4.5/Q.931 � both � M � 4-32 � 쳐컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컵컴컴컴컴컴컴탠컴컴컴컴컴컴탠컴컴컴컴캑 � Display � 4.5/Q.931 � n -> u � O(Note 1) � (Note 2)� 읕컴컴컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴컴컨컴컴컴컴컴컴좔컴컴컴컴컴컴좔컴컴컴컴켸 Note 1 - Included if the network provides information that can be presented to the user. Note 2 - The minimum length is 2 octets. The maximum length is network dependent and is either 34 or 82 octets. 8. General message format and information element coding This section should be read in conjunction with  4 of Recommendation Q.931 and contains the coding of the information elements specifically used by the procedures described in this Recommendation. 8.1 Message type The following additional codings are defined for message type. TABLE 8-1/Q.932 Q.932 Message types (3276) - 8 - AP IX-127-E 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴커 � 8 7 6 5 4 3 2 1 � � � � � � 0 0 1 - - - - - (Q.931 call information phase message group) � � � � 0 0 1 0 0 - HOLD � � � � 0 1 0 0 0 - HOLD ACKNOWLEDGE � � � � 1 0 0 0 0 - HOLD REJECT � � � � 1 0 0 0 1 - RETRIEVE � � � � 1 0 0 1 1 - RETRIEVE ACKNOWLEDGE � � � � 1 0 1 1 1 - RETRIEVE REJECT � � � � � � 0 1 1 - - - - - (Q.931 miscellaneous message group) � � � � 0 0 0 1 0 - FACILITY � � � � 0 0 1 0 0 - REGISTER � 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴켸 8.2 Other information elements These information elements are coded according to the general coding rules as defined in  4.5.1 of Recommendation Q.931. Note - The value used for Protocol discriminator shall be as defined for messages used in Recommendation Q.931. Table 8-2/Q.932 contains the codepoints allocated to the information elements defined in this Recommendation. TABLE 8-2/Q.932 Information elements specific to supplementary service control 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴쩡컴컴컴컴쩡컴컴컴컴� � 쿞ection � Maximum � � 퀁eference� length � � 8 7 6 5 4 3 2 1 � � (octets)� � � � Note 1 � � 쳐컴컴컴컴탠컴컴컴컴� � � � � � 0 : : : : : : : Variable length information � � � � elements � � � � � � � (3276) - 9 - AP IX-127-E � 0 0 1 1 1 0 0 Facility � 8.2.2 � Note 3 � � � � � � 0 1 1 0 0 1 0 Information request � 8.2.5 � 3 � � � � � � 0 1 1 1 0 0 0 Feature activation � 8.2.3 � 4 � � � � � � 0 1 1 1 0 0 1 Feature indication � 8.2.4 � 5 � � � � � � 0 1 1 1 0 1 0 Service profile identification� 8.2.6 � 32 � � � � � � 0 1 1 1 0 1 1 Endpoint identifier � 8.2.1 � 4 � � � � � � � � � � All other values are reserved (Note 2). � � � 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴좔컴컴컴컴좔컴컴컴컴� Note 1 - The length limits described for the variable length information elements below take into account only the present CCITT standardized coding values. Future enhancements and extensions to this Recommendation will not be restricted to these limits. Note 2 - The reserved values with bits 5-8 coded "0 e for future information elements for which comprehension by the receiver is required (see  5.8.7.1 of Recommendation Q.931). Note 3 - The maximum length of the Facility information element is application dependent consistent with the maximum length of the message. 8.2.1 Endpoint identifier The purpose of the Endpoint identifier information element is: - to indicate the user service identifier and terminal identifier for the purpose of terminal identification; and - to indicate a specific terminal for the purpose of terminal selection. (See Annex A for the associated procedures.) The Endpoint identifier information element is coded as shown in Figure 8-1/Q.932 and Table 8-3/Q.932. The default maximum length of the Endpoint identifier information element is four octets. 8 7 6 5 4 3 2 1 旼컴컫컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� � � Endpoint identifier � � � � � 0 � 0 1 1 1 0 1 1 � Octet 1 � � � � 쿔nformation element identifier � 쳐컴컨컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� (3276) - 10 - AP IX-127-E � Length of Endpoint identifier � 2 � contents � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� � 1 � User service identifier � 3 � Ext� � 쳐컴컵컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� � 1 � Interpreter Terminal identifier� 4* � Ext� � 읕컴컨컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� * This octet is optional. FIGURE 8-1/Q.932 Endpoint identifier information element TABLE 8-3a/Q.932 Endpoint identifier information element User service identifier (USID) (octet 3) The USID is a selection parameter which identifies a group of terminals on an interface which share a common service profile and which may be addressed together. Upon receipt of this element, a terminal will consider itself as being addressed if the value received matches its stored value or if the value received is coded as all "1"s (127). When USID is coded as 127, octet 4 is not used. Interpreter (octet 4) Bit 7 of octet 4 indicates how a terminal is to interpret the TID field received. When set to "0", the terminal is being addressed only if the TID matches (see TID definition following). When set to "1", the terminal is being addressed only if the TID received is not 63 and does not match. In the user-to-network direction, this bit is set to "0". TABLE 8-3b/Q.932 Endpoint identifier information element Terminal identifier (TID) (octet 4) The TID is a selection parameter which identifies a single terminal within a group designated by a USID value. For USID = 127, the TID does not apply. Upon receipt to this field, a terminal will consider itself addressed if one of the following is true: - the interpreter bit = "0" and the value received matches the terminal's stored value; - the interpreter bit = "1" and the value received does not match the terminal's stored value; (3276) - 11 - AP IX-127-E - the value received is coded all "1"s (63). 8.2.2 Facility This section defines only the structure and the coding of the Facility information element. Specific procedures that will be required are subject to further study in relation to future Recommendations on specific supplementary services. The purpose of the Facility information element is to indicate the invocation and operation of supplementary services, identified by the corresponding operation value within the Facility information element. The Facility information element is defined in Figures 8-2 to 8-5/Q.932 and Tables 8-4 to 8-20/Q.932. The Facility information element may be repeated in a given message. The maximum length of the Facility information element is application dependent consistent with the maximum length of the message. 8 7 6 5 4 3 2 1 旼컴컴쩡컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� � � Facility � � � � � 0 � 0 0 1 1 1 0 0 � Octet 1 � � � � � Information element identifier � 쳐컴컴좔컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� � Length of facility contents � 2 쳐컴컴쩡컴컴컴컴쩡컴컴컴컴컴컴컴컴컴컴컴컴� � 1 � 0 0 � � � Ext � Spare � Service discriminator � 3 쳐컴컴좔컴컴컴컴좔컴컴컴컴컴컴컴컴컴컴컴컴� � Component(s) (Note) � 4, etc. 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� Note - One or more components may be included depending on specific service requirements. FIGURE 8-2/Q.932 Facility information element TABLE 8-4/Q.932 Facility information element Service discriminator Bits 5 4 3 2 1 1 0 0 0 1 Discriminator for supplementary service applications All other values are reserved and their usage is the subject of other Recommendations. (3276) - 12 - AP IX-127-E 8.2.2.1 Component (Octets 4, etc.) This specification makes use of and is a subset of Recommendations X.208[7] (Specification of Abstract Syntax Notation One (ANS.1)), X.209[8] (Specification of basic encoding rules for Abstract Syntax Notation One (ANS.1)), X.219[9] (Remote operations: model, notation and service definition) and X.229[10] (Remote operations: protocol specification). Based on Recommendations X.208 and X.209, the following specific encodings apply. A component is a sequence of data elements each of which is made up of a tag, a length and a contents. The component type is indicated by the first octet of the Facility information element component. The component types defined for the Facility information element are: - Invoke - Return result - Return error - Reject. Note 1 - Recommendation X.229 which defines the Remote Operations Service Element (ROSE) uses the term Application Protocol Data Unit (APDU) in place of component. However since this protocol element may be applied to the support of network layer services and of application layer services, the term "component" is more appropriate in the context of this Recommendation. Tables 8-5 to 8-8/Q.932 show the structure of these component types. Note 2 - See Appendix III for a general description of the component coding and formatting principles. (3276) - 13 - AP IX-127-E TABLE 8-5/Q.932 Invoke component 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴컫컴컴컴컴컴컴컴컴컴컴컴쩡컴컴컴컴컴컴� � Invoke component � Reference � Mandatory indication � Octet group � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴� � Component type tag � 8.2.2.3 � Mandatory � 4 � � Component length (Note 1)� 8.2.2.2 � � 5 � � 旼컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴� � � Invoke identifier tag � 8.2.2.4 � � 6 � � � Invoke identifier length � 8.2.2.2 � Mandatory � 7 � � � Invoke identifier � � � 8 � � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴� � � Linked identifier tag � 8.2.2.4 � � 9 � � � Linked identifier length � 8.2.2.2 � Optional � 10 � � � Linked identifier � � � 11 � � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴� � � Operation value tag � 8.2.2.5 � � 12 � � � Operation value length � 8.2.2.2 � Mandatory � 13 � � � Operation value � (Note 3) � � 14 � � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴� � � Argument (Note 2) � 8.2.2.8 � Optional � 15, etc. � � � � (Note 3) � � � 읕좔컴컴컴컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴컨컴컴컴컴컴컴컴컴컴컴컴좔컴컴컴컴컴컴� Note 1 - The component length is coded to indicate the number of octets contained in the component (excluding the component type tag and the component length octets). Note 2 - This is a parameter of the invoke component type. Note 3 - The coding is supplementary service specific and the subject of other Recommendations. TABLE 8-6/Q.932 Return result component 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴쩡컴컴컴컴쩡컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴커 � Return result component 쿝eference쿘andatory indication쿚ctet group� 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴탠컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴캑 � Component type tag � 8.2.2.3 � Mandatory � 4 � � Component length (Note 3)� 8.2.2.2 � � 5 � � 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴� � � Invoke identifier tag � 8.2.2.4 � � 6 � � � Invoke identifier length � 8.2.2.2 � Mandatory � 7 � � � Invoke identifier � � � 8 � � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴� � � Sequence tag � 8.2.2.8 � Optional � 9 � � � Sequence length (Note 4) � 8.2.2.2 � (Note 1) � 10 � � � 旼컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴탠컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴캑 � � 쿚peration value tag � 8.2.2.5 � � 11 � � � 쿚peration value length � 8.2.2.2 � Optional � 12 � � � 쿚peration value � (Note 6)� (Note 2) � 13 � (3276) - 14 - AP IX-127-E � � 쳐컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴탠컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴캑 � � 쿝esult (Note 5) � 8.2.2.8 � Optional � 14, etc. � � � � � (Note 6)� � � 읕컨컴좔컴컴컴컴컴컴컴컴컴컴컴컴좔컴컴컴컴좔컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴켸 Note 1 - If the return result component does not include any result, then the sequence and operational value shall be omitted. Table 8-19 indicates the encoding for the sequence tag. Note 2 - If a result is included, then the operation value is mandatory and is the first element in the sequence. Note 3 - The component length is coded to indicate the number of octets contained in the component (excluding the component type tag and the component length octets). Note 4 - The sequence length is coded to indicate the number of octets contained in the sequence (excluding the sequence type tag and the sequence length octets). Note 5 - This is a parameter of the return result component type. Note 6 - The coding is supplementary service specific and the subject of other Recommendations. TABLE 8-7/Q.932 Return error component 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴쩡컴컴컴컴쩡컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴커 � Return error component 쿝eference쿘andatory indication쿚ctet group� 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴탠컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴캑 � Component type tag � 8.2.2.3 � Mandatory � 4 � � Component length (Note 1)� 8.2.2.2 � � 5 � � 旼컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴� � � Invoke identifier tag � 8.2.2.4 � � 6 � � � Invoke identifier length � 8.2.2.2 � Mandatory � 7 � � � Invoke identifier � � � 8 � � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴� � � Error value tag � 8.2.2.6 � � 9 � � � Error value length � 8.2.2.2 � Mandatory � 10 � � � Error value � � � 11 � � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴� � � Parameter (Note 2) � 8.2.2.8 � Optional � 12, etc. � � � � (Note 3)� � � 읕컨컴컴컴컴컴컴컴컴컴컴컴컴컴좔컴컴컴컴좔컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴켸 Note 1 - The component length is coded to indicate the number of octets contained in the component (excluding the component type tag and the component length octets). Note 2 - This is a parameter of the return result component type. Note 3 - The coding is supplementary service specific and the subject of other Recommendations. (3276) - 15 - AP IX-127-E TABLE 8-8/Q.932 Reject component 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컫컴컴컴컴컫컴컴컴컴컴컴컴컴컴컴쩡컴컴컴컴컴� � Reject component 쿝eference쿘andatory indication쿚ctet group� 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴� � Component type tag � 8.2.2.3 � Mandatory � 4 � � Component length (Note) � 8.2.2.2 � � 5 � � 旼컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴탠컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴캑 � 쿔nvoke identifier tag � 8.2.2.4 � � 6 � � 쿔nvoke identifier length � 8.2.2.2 � Mandatory � 7 � � 쿔nvoke identifier � � � 8 � � 쳐컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴탠컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴캑 � 쿛roblem tag � 8.2.2.7 � � 9 � � 쿛roblem length � 8.2.2.2 � Mandatory � 10 � � 쿛roblem � 8.2.2.7 � � 11 � 읕컨컴컴컴컴컴컴컴컴컴컴컴컴컨컴컴컴컴컨컴컴컴컴컴컴컴컴컴컴좔컴컴컴컴컴� Note - The component length is coded to indicate the number of octets contained in the component (excluding the component type tag and the component length octets). 8.2.2.2 Length of each component or of their data elements Lengths up to 127 octets are coded using the short form of Recommendation X.209: bit 8 is set to zero and the remaining seven bits are a binary encoding of the length, with bit 1 the least significant bit. (This length encoding is identical to that of Recommendation Q.931 for lengths up to 127 octets.) This is illustrated in Figure 8-3/Q.932. 8 7 6 5 4 3 2 1 旼컫컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� �0 � Length of contents � � 쿘SB LSB� 읕컨컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� FIGURE 8-3/Q.932 Format of the length field (short form) If the Length of the contents is greater than 127 octets, then the long form of the length of the contents is used. The long form length is from 2 to 127 octets long. Bit 8 of the first octet is coded 1, and bits 1 to 7 of the first octet encode a number one less than the size of the length in octets as an unsigned binary number whose MSB and LSB are bits 7 and 1, respectively. The length itself is encoded as an unsigned binary number whose MSB and LSB are bit 8 of the second octet and bit 1 of the last octet, respectively. This binary number should be encoded in the fewest possible octets, with no leading octets having the value 0. This is illustrated in Figure 8-4/Q.932. 8 7 6 5 4 3 2 1 旼컴쩡컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� �1 �(Length of field size)-1 � (3276) - 16 - AP IX-127-E � 쿘SB LSB� 쳐컴좔컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿘SB � � Length of contents � � LSB� 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� FIGURE 8-4/Q.932 Format of the length field (long form) Note - The application of the indefinite form of the length is not precluded depending on future applications (see Appendix III.3). 8.2.2.3 Component type tag The coding of the component type tag is shown in Table 8-9/Q.932. TABLE 8-9/Q.932 Component type tag 旼컴컴컴컴컴컴컴컴컴컴쩡컴컴컴컴컴컴컴컴컴컴컴컴� 쿎omponent type tag � 8 7 6 5 4 3 2 1 � 쳐컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴� 쿔nvoke � 1 0 1 0 0 0 0 1 � 쿝eturn result � 1 0 1 0 0 0 1 0 � 쿝eturn error � 1 0 1 0 0 0 1 1 � 쿝eject � 1 0 1 0 0 1 0 0 � 읕컴컴컴컴컴컴컴컴컴컴좔컴컴컴컴컴컴컴컴컴컴컴컴� 8.2.2.4 Component identifier tags An invoke identifier is used to identify an operation invocation and is reflected in the return result or return error that responds to it. An invoke may refer to another invoke through the linked identifier. When a protocol error occurs, the invoke identifier is reflected in the reject component, but if it is not available, a null is returned. Invoke and linked identifiers are one octet long. The null has zero length. The coding of the component identifier tags is shown in Table 8-10/Q.932. TABLE 8-10/Q.932 Coding of component identifier tag 旼컴컴컴컴컴컴컴컴컴컴컴쩡컴컴컴컴컴컴컴컴컴컴컴컴� � � 8 7 6 5 4 3 2 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴� 쿔nvoke identifier � 0 0 0 0 0 0 1 0 � 쿗inked identifier � 1 0 0 0 0 0 0 0 � 쿙ull � 0 0 0 0 0 1 0 1 � 읕컴컴컴컴컴컴컴컴컴컴컴좔컴컴컴컴컴컴컴컴컴컴컴컴� 8.2.2.5 Operation value tag (3276) - 17 - AP IX-127-E The operation value specifies the facility or supplementary service application and operation being requested. Values are encoded as integers. The value of the operation value is supplementary service specific and will be specified in future Recommendations which contain the protocol for individual supplementary services. The coding for the operation value tag is shown in Table 8-11/Q.932. TABLE 8-11/Q.932 Coding of operation value tag 旼컴컴컴컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴컴컴컴컴컴컴컴커 � � 8 7 6 5 4 3 2 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴캑 쿚peration value tag � 0 0 0 0 0 0 1 0 � 읕컴컴컴컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴컴컴컴컴컴컴컴켸 8.2.2.6 Error value tag Operations report errors as specified for each individual operation. Values are encoded as integers. The coding for the error value tag is shown in Table 8-12/Q.932. TABLE 8-12/Q.932 Coding of error value tag 旼컴컴컴컴컴컴컴컴컴컴컴쩡컴컴컴컴컴컴컴컴컴컴컴컴� � � 8 7 6 5 4 3 2 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴� 쿐rror value tag � 0 0 0 0 0 0 1 0 � 읕컴컴컴컴컴컴컴컴컴컴컴좔컴컴컴컴컴컴컴컴컴컴컴컴� 8.2.2.7 Problem tag Protocol problems are indicated in groups. Table 8-13/Q.932 indicates the tags for these groups. The contents for each of these tags is indicated in Tables 8-14 to 8-17/Q.932. The contents of these tags are defined in Table 8-18/Q.932. TABLE 8-13/Q.932 Coding of problem tags 旼컴컴컴컴컴컴컴컴컴컴컴컴컴쩡컴컴컴컴컴컴컴컴컴컴컴컴� 쿛roblem � 8 7 6 5 4 3 2 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴� 쿒eneral problem � 1 0 0 0 0 0 0 0 � 쿔nvoke problem � 1 0 0 0 0 0 0 1 � 쿝eturn result problem � 1 0 0 0 0 0 1 0 � 쿝eturn error problem � 1 0 0 0 0 0 1 1 � 읕컴컴컴컴컴컴컴컴컴컴컴컴컴좔컴컴컴컴컴컴컴컴컴컴컴컴� TABLE 8-14/Q.932 Coding of general problem (3276) - 18 - AP IX-127-E 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴컴컴컴컴컴컴컴커 � � 8 7 6 5 4 3 2 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴캑 쿢nrecognized component � 0 0 0 0 0 0 0 0 � 쿘istyped component � 0 0 0 0 0 0 0 1 � 쿍adly structured component � 0 0 0 0 0 0 1 0 � 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴컴컴컴컴컴컴컴켸 Note - ROSE uses the term Application Protocol Data Unit (APDU) in place of component. TABLE 8-15/Q.932 Coding of invoke problem 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴컴컴컴컴컴컴컴커 � � 8 7 6 5 4 3 2 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴캑 쿏uplicate invocation � 0 0 0 0 0 0 0 0 � 쿢nrecognized operation � 0 0 0 0 0 0 0 1 � 쿘istyped argument � 0 0 0 0 0 0 1 0 � 쿝esource limitation � 0 0 0 0 0 0 1 1 � 쿔nitiator releasing � 0 0 0 0 0 1 0 0 � 쿢nrecognized linked identifier� 0 0 0 0 0 1 0 1 � 쿗inked response unexpected � 0 0 0 0 0 1 1 0 � 쿢nexpected child operation � 0 0 0 0 0 1 1 1 � 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴컴컴컴컴컴컴컴켸 TABLE 8-16/Q.932 Coding of return result problem 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴컴컴컴컴컴컴컴커 � � 8 7 6 5 4 3 2 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴캑 쿢nrecognized invocation � 0 0 0 0 0 0 0 0 � 쿝esult response unexpected � 0 0 0 0 0 0 0 1 � 쿘istyped result � 0 0 0 0 0 0 1 0 � 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴컴컴컴컴컴컴컴켸 TABLE 8-17/Q.932 Coding of return error problem 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴쩡컴컴컴컴컴컴컴컴컴컴컴컴� � � 8 7 6 5 4 3 2 1 � 쳐컴컴컴컴컴컴컴컴컴컴컴컴컴컴탠컴컴컴컴컴컴컴컴컴컴컴컴� 쿢nrecognized invocation � 0 0 0 0 0 0 0 0 � 쿐rror response unexpected � 0 0 0 0 0 0 0 1 � 쿢nrecognized error � 0 0 0 0 0 0 1 0 � 쿢nexpected error � 0 0 0 0 0 0 1 1 � 쿘istyped parameter � 0 0 0 0 0 1 0 0 � (3276) - 19 - AP IX-127-E 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴좔컴컴컴컴컴컴컴컴컴컴컴컴� TABLE 8-18/Q.932 Problem code definitions 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� 쿒eneral-problem: � � � �- unrecognized-component: signifies that the type of the component,� � as evidenced by its Type Identifier, is � � not one of the four defined by � � Recommendation X.229[10] � � � �- mistyped-component: signifies that the structure of the � � component does not conform to � � Recommendation X.229 � � � �- badly-structured-component: signifies that the structure of the � � component does not conform to the � � standard notation and encoding, defined � � in Recommendations X.208[7] and X.209[8] � � � 쿔nvoke-problem: � � � �- duplicate-invocation: signifies that the Invoke-identifier � � parameter violates the assignment rules � � of Recommendation X.219[9] � � � �- unrecognized-operation: signifies that the operation is not one � � of those agreed between the user and the � � network � � � �- mistyped-argument: signifies that the type of the operation � � argument supplied is not that agreed � � between the user and the network � � � �- resource-limitation: the performing user or network is not � � able to perform the invoked operation � � due to resource limitation � � � �- initiator-releasing: the association-initiator is not willing � � to perform the invoked operation because � � it is about to attempt to release the � � application-association � � � �- unrecognized-linked-identifier: signifies that there is no operation in � � progress with an Invoke-identifier equal � � to the specified Linked-identifier � � � �- linked-response-unexpected: signifies that the invoked operation � � referred to by the Linked-identifier is � � not a parent-operation � � � �- unexpected-child-operation: signifies that the invoked child- � (3276) - 20 - AP IX-127-E � operation is not one that the invoked � � parent-operation referred to by the � � Linked-identifier allows � 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� (3276) - 21 - AP IX-127-E 旼컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� � � 쿝eturn-result-problem: � � � �- unrecognized-invocation: signifies that no operation with the � � specified Invoke-identifier is in � � progress � � � �- result-response-unexpected: signifies that the invoked operation � � does not report a result � � � �- mistyped-result: signifies that the type of the Result � � parameter supplied is not that agreed � � between the user and the network � � � 쿝eturn-error-problem: � � � �- unrecognized-invocation: signifies that no operation with the � � specified Invoke-identifier is in � � progress � � � �- error-response-unexpected: signifies that the invoked operation � � does not report failure � � � �- unrecognized-error: signifies that the reported error is not � � one of those agreed between the user � � and the network � � � �- unexpected-error: signifies that the reported error is not � � one that the invoked operation may report� � � �- mistyped-parameter: signifies that the type of the error � � parameter supplied is not that agreed � � between the user and the network � 읕컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴컴� Note - The former definitions are adapted from  7.4.4.2 and 7.5.4.2 of Recommendation X.229 (Remote Operations: Protocol Specification). 8.2.2.8 Parameters The parameters included with a component (i.e., the argument with an invoke, the result with a return result or the parameter with a return error) are indicated in the specification of the operation. They may include optional and default parameters. Parameters shall be one of the following: - a sequence of parameters - a set of parameters - a specific parameter with its own tag - nothing at all (i.e., absent). When more than one parameter is required, they shall follow a sequence or set tag as specified in the specification of the operation. (The usage of the sequence and set tags is defined in Recommendations X.208/X.209.) (3276) - 22 - AP IX-127-E Sequences and sets of parameters may contain further sequences and sets as specified for the operation to be performed. Table 8-19/Q.932 indicates the coding of the sequence and set tags. TABLE 8-19/Q.932 Coding of sequence and set tags 旼컴컴컴컴컴컴컴컴컴컴컫컴컴컴컴컴컴컴컴컴컴컴컴커 � � 8 7 6 5 4 3 2 1 � 쳐컴컴컴컴컴컴컴컴컴컴컵컴컴컴컴컴컴컴컴컴컴컴컴캑 쿞equence tag � 0 0 1 1 0 0 0 0 � 쿞et tag � 0 0 1 1 0 0 0 1 � 읕컴컴컴컴컴컴컴컴컴컴컨컴컴컴컴컴컴컴컴컴컴컴컴켸 8.2.2.9 Treatment of existing Recommendation Q.931 information elements as parameters Supplementary service protocol specifications are expected to require new parameters to be defined and to require existing Recommendation Q.931 information elements (Note 1). New parameters shall be defined using Recommendation X.209 coding if they do not appear elsewhere in Q.931 messages. Supplementary service protocol specifiers may elect to encapsulate one or more existing Recommendation Q.931 information elements within a Recommendation X.209 data element, thereby retaining the Recommendation Q.931 coding for these information elements. When this option is chosen, all the Recommendation Q.931 information elements should be grouped together as the content following the Recommendation Q.931 information elements tag. This is illustrated in Figure 8-5/Q.932. The tag is defined in Table 8-20/Q.932. This data element may appear by itself or as a member of a sequence or set as indicated in  8.2.2.8. Note 1 - Encapsulation of the Facility information element within Facility information elements shall not be used. (3276) - 23 - AP IX-127-E FIGURE 8-5/Q.932 Encapsulation of Q.931 information elements TABLE 8-20/Q.932 Q.931 information elements tag Note - All other values are reserved but this approach may also be applied in the future to coding structures from other Recommendations by defining other tags as required. (3276) CCITT\AP-IX\DOC\127E2.TXS