24.3013GPPNon-Access-Stratum (NAS) protocol for Evolved Packet System (EPS)Release 18Stage 3TS
The different formats (V, LV, T, TV, TLV, LV-E, TLV-E) and the five categories of information elements (type 1, 2, 3, 4 and 6) are defined in 3GPP TS 24.007 .
The first octet of an information element in the non-imperative part contains the IEI of the information element. If this octet does not correspond to an IEI known in the message, the receiver shall determine whether this IE is of type 1 or 2 (i.e. it is an information element of one octet length) or an IE of type 4 (i.e. that the next octet is the length indicator indicating the length of the remaining of the information element) (see 3GPP TS 24.007 ).
This allows the receiver to jump over unknown information elements and to analyse any following information elements.
The definitions of information elements which are common for the EMM and ESM protocols or which are used by access stratum protocols are described in clause 9.9.2.
The information elements of the EMM or ESM protocols can be defined by reference to an appropriate specification, e.g., "see clause 10.5.6.3 in 3GPP TS 24.008 ".