Section: 10.5 Other information elements
Content: The different formats (V, LV, T, TV, TLV) and the five categories of information elements (type 1, 2, 3, 4, and 6) are defined in 3GPP TS 24.007[ Mobile radio interface signalling layer 3; General Aspects ]  [20]. 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), 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) or an IE of type 6 (i.e. that the next 2 octets are the length indicator indicating the length of the remaining of the information element (see 3GPP TS 24.007[ Mobile radio interface signalling layer 3; General Aspects ]  [20]). This allows the receiver to jump over unknown information elements and to analyse any following information elements. The information elements which are common for at least two of the three protocols Radio Resources management, Mobility Management and Call Control, are listed in subclause 10.5.1. The information elements for the protocols Mobility Management and Call Control are listed in subclauses 10.5.3 and 10.5.4 respectively. Default information element identifiers are listed in annex K. NOTE: Different information elements may have the same default information element identifier if they belong to different protocols. The descriptions of the information element types in subclauses 10.5.1, 10.5.3, and 10.5.4 are organized in alphabetical order of the IE types. Each IE type is described in one subclause. The subclause may have an introduction: - possibly explaining the purpose of the IE; - possibly describing whether the IE belongs to type 1, 2, 3, 4 or 5; - possibly indicating the length that the information element has if it is either type 5 or if it is used in format TV (type 1 and 3) or TLV (type 4). A figure of the subclause defines the structure of the IE indicating: - possibly the position and length of the IEI. (However it depends on the message in which the IE occurs whether the IE contains an IEI.); - the fields the IE value part is composed of; - possibly the position and length of the length indicator. (However it depends on the IE type whether the IE contains a length indicator or not.); - possibly octet numbers of the octets that compose the IE (see clause a) below). Finally, the subclause contains tables defining the structure and value range of the fields that compose the IE value part. The order of appearance for information elements in a message is defined in clause 9. The order of the information elements within the imperative part of messages has been chosen so that information elements with 1/2 octet of content (type 1) go together in succession. The first type 1 information element 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. If the number of type 1 information elements is odd then bits 5 to 8 of the last octet occupied by these information elements contains a spare half octet IE in format V. Where the description of information elements in the present document contains bits defined to be "spare bits", these bits shall set to the indicated value (0 or 1) by the sending side, and their value shall be ignored by the receiving side. With few exceptions, spare bits are indicated as being set to "0" in 3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ] .