04.083GPPMobile radio interface Layer 3 specificationRelease 1998TS
This sub-clause defines the structure of the messages of those layer 3 protocols defined in 3GPP TS 04.08. These are standard L3 messages as defined in 3GPP TS 04.07 with the exception of those sent on the SCH, RACH, and the HANDOVER ACCESS message.
Each definition given in the present sub-clause includes:
a) a brief description of the message direction and use, including whether the message has:
1. Local significance, i.e. relevant only on the originating or terminating access;
2. Access significance, i.e. relevant in the originating and terminating access, but not in the network;
3. Dual significance, i.e. relevant in either the originating or terminating access and in the network; or
4. Global significance, i.e. relevant in the originating and terminating access and in the network.
b) a table listing the information elements known in the message and their order of their appearance in the message. In messages for circuit-switched call control also a shift information element shall be considered as known even if not included in the table. All information elements that may be repeated are explicitly indicated. ( V and LV formatted IEs, which compose the imperative part of the message, occur before T, TV, and TLV formatted IEs which compose the non-imperative part of the message, cf. 3GPP TS 04.07.) In a (maximal) sequence of consecutive information elements with half octet length, the first information element with half octet length occupies bits 1 to 4 of octet N, the second bits 5 to 8 of octet N, the third bits 1 to 4 of octet N+1 etc. Such a sequence always has an even number of elements.
For each information element the table indicates:
1. the information element identifier, in hexadecimal notation, if the IE has format T, TV, or TLV. Usually, there is a default IEI for an information element type; default IEIs of different IE types of the same protocol are different. If the IEI has half octet length, it is specified by a notation representing the IEI as a hexadecimal digit followed by a "-" (example: B-).
NOTE The same IEI may be used for different information element types in different messages of the same protocol.
2. the name of the information element (which may give an idea of the semantics of the element). The name of the information element (usually written in italics) followed by "IE" or "information element" is used in 3GPP TS 04.08 as reference to the information element within a message.
3. the name of the type of the information element (which indicates the coding of the value part of the IE), and generally, the referenced sub-clause of clause 10 of 3GPP TS 04.08 describing the value part of the information element.
4. the presence requirement indication (M, C, or O) for the IE as defined in 3GPP TS 04.07.
5. The format of the information element (T, V, TV, LV, TLV) as defined in 3GPP TS 04.07.
6. The length of the information element (or permissible range of lengths), in octets, in the message, where "?" means that the maximum length of the IE is only constrained by link layer protocol, and in the case of the Facility IE by possible further conditions specified in 3GPP TS 04.10. This indication is non-normative.
c) sub-clauses specifying, where appropriate, conditions for IEs with presence requirement C or O in the relevant message which together with other conditions specified in 3GPP TS 04.08 define when the information elements shall be included or not, what non-presence of such IEs means, and – for IEs with presence requirement C – the static conditions for presence and/or non-presence of the IEs (cf. 3GPP TS 04.07).