Provides: a) the description of a means to permit a protocol to be identified; b) a record of the structure and allowable ranges of protocol identifier(s) which can be assigned by ISO/IEC JTC1 SC6, CCITT and other authorities; c) a record of the values of protocol identifiers used by OSI Network Layer protocols and non-OSI protocols occupying a similar position, in particular, only protocols with protocol control information commencing in octet 1 of the protocol data unit are covered; and d) a record of the values that are in use as protocol control information in non-Network Layer protocols where they impact on Network Layer protocol identification.

ISO/IEC TR 9577 : 1999(R2015) - Identical