Information technology — Use of X.25 Packet Layer Protocol in conjunction with X.21/X.21 bis to provide the OSI connection-mode Network Service
信息技术——使用X.25数据包层协议和X.21/X.21 bis提供OSI连接模式网络服务
Applies to environments including a CSDN and an ISDN terminal adaptor complying with recommendation X.30 which provides an X.21 access. Provision is achieved by specifying the mapping of the CONS primitives and parameters to and from the elements of the protocols used (X.25 PLP and X.21).