This Standard specifies the characteristics of the data link layer protocol for use on the D-channel at the S reference point provided by a Private Telecommunication Network (PTN). The purpose of the data link layer protocol is to convey information between network layer entities using the D-channel.
This Standard is applicable to Terminal Equipment (TE) (including Terminal Adaptors) and Private Telecommunication Network Exchanges (PTNXs) interconnected at the S reference point.