Specifies the procedures, formats and optional user facilities at the packet level for Data Terminal Equipment (DTE) operating in conformance with CCITT Recommendation X.25. Both virtual call and permanent virtual circuit modes of operation are covered. It also provides guidelines for private networks that use CCITT Recommendation X.25 to connect to packet-switched public data networks and that may also offer an X.25 interface to DTE. This Standard is technically identical to ISO 8208:1987.