Section: 8 Handling of unknown, unforeseen, and erroneous protocol data 8.1 General
Content: The procedures specified in 3GPP TS 24.008[ Mobile radio interface Layer 3 specification; Core network protocols; Stage 3 ]  and call-related supplementary service handling in 3GPP TS 24.010[ Mobile radio interface  layer 3; Supplementary services specification; General aspects ]  [21] apply to those messages which pass the checks described in this subclause. This subclause also specifies procedures for the handling of unknown, unforeseen, and erroneous protocol data by the receiving entity. These procedures are called "error handling procedures", but in addition to providing recovery mechanisms for error situations they define a compatibility mechanism for future extensions of the protocols. Error handling concerning the value part of the Facility IE and of the SS Version Indicator IE are not in the scope of the present document. It is defined in 3GPP TS 24.010[ Mobile radio interface  layer 3; Supplementary services specification; General aspects ]  [21] and the 3GPP TS 24.08[ None ] x series. Sub subclauses 8.1 to 8.8 shall be applied in order of precedence. Most error handling procedures are mandatory for the mobile station. Detailed error handling procedures in the network are implementation dependent and may vary from PLMN to PLMN. However, when extensions of this protocol are developed, networks will be assumed to have the error handling that is indicated in this subclause as mandatory ("shall") and that is indicated as strongly recommended ("should"). Subclauses 8.2, 8.3, 8.4, 8.5 and 8.7.2 do not apply to the error handling in the network applied to the receipt of initial layer 3 message: If the network diagnoses an error described in one of these subclauses in the initial layer 3 message received from the mobile station, it shall either: - try to recognize the classmark and then take further implementation dependent actions; or - release the RR-connection. Also, the error handling of the network is only considered as mandatory or strongly recommended when certain thresholds for errors are not reached during a dedicated connection. For definition of semantical and syntactical errors see 3GPP TS 24.007[ Mobile radio interface signalling layer 3; General Aspects ]  [20], subclause 11.4.2.