scope:

This International Standard specifies general principles for the mappings between the OS1 Data Link service (ISO/IEC 8886), both connection-mode (CO-DLS) and connectionless-mode (CL-DLS), and standard Data Link protocols, as follows:

M1: CO-DLS - HDLC X.25 LAPB-compatible DTE procedures, single link procedures (ISO/IEC 7776)

M2: CO-DLS - HDLC Unbalnnced operation Noi-m;d response niode Class.

M3: CO-DLS - Logical link control (LLC) Type 2 (ISO/IEC 8802-2)

M4: CL-DLS - LLC Type 1 (ISO/IEC 8802-2)

M5: CL-DLS - LLC HDLC Bnlnnced operation Coi~nectionless-nio~Cel ass, BCC (ISOIIEC 3309, ISO/IEC 4335 and ISO/IEC 7809)

M6: CL-DLS - HDLC Unbalanced operation Connectionless-mode Class. UCC (ISO/IEC 3309, ISO/rEC 4335 and ISOflEC 7809)

This International Standard specifies the detailed mappings M1. M2, M5 and MG; it also specifies the nuin features of the mappings M3 and M4.

This International Standard does not specify individual implementations or products, nor does it constrain the implementation of Data Link entities and interfaces within an information processing system. NOTES

1 The above designations M1 to M6 for the mappings are used elsewhere in this 1ntern:itionnl Standard.

2 The possibility of adding further mappings to the above list in the future is not precluded (for example, to cover Frame Relay protocols).