SNA Server maintains a unique identification for every LU 6.2 session it has with a remote LU. This 8-byte identifier is generated by SNA Server every time it starts a new session (or is received by SNA Server when a session is initiated remotely). The Sync Point resynchronization protocols require knowledge of the session identifier.
To provide this, the MC_GET_ATTRIBUTES and the GET_ATTRIBUTES verbs have been modified to return the session identifier of the session over which a particular conversation is allocated. The MC_GET_ATTRIBUTES and GET_ATTRIBUTES verbs can be used to retrieve this sess_id field of the VCB if the opext field of the VCB is combined with the value AP_EXTD_VCB using OR before calling APPC.