The contents of each SLPP message is specified in
clause 6.2 using ASN.1 to specify the message syntax and using tables when needed to provide further detailed information about the fields specified in the message syntax. The syntax of the information elements that are defined as stand-alone abstract types is further specified in a similar manner in
clause 6.3.
The ASN.1 in this clause uses the same format and coding conventions as described in
Annex A of
TS 38.331.
Transfer syntax for SLPP messages is derived from their ASN.1 definitions by use of Basic Packed Encoding Rules (BASIC-PER), Unaligned Variant, as specified in
ITU-T Rec. X.691 [4]. The encoded SLPP message always contains a multiple of 8 bits.
Transfer syntax for SLPP IEs is derived from their ASN.1 definitions by use of Basic Packed Encoding Rules (BASIC-PER), Unaligned Variant, as specified in
ITU-T Rec. X.691 [4]. The encoded SLPP IE always contains a multiple of 8 bits. This applies when a single SLPP IE is encoded as the basic production, i.e. for other purposes than encoding the SLPP IE within an SLPP message.
When specifying information elements which are to be represented by BIT STRINGs, if not otherwise specifically stated in the field description of the concerned IE or elsewhere, the following principle applies with regards to the ordering of bits:
-
The first bit (leftmost bit) contains the most significant bit (MSB);
-
the last bit (rightmost bit) contains the least significant bit (LSB).