participant-index

    OpenVMS usage longword_unsigned
    type          longword (unsigned)
    access        read only
    mechanism     by reference
    Index of the caller within this application. The participant-
    index argument is the address of an unsigned longword that
    contains this index. Participant-index is assigned at process
    creation time and is unique for each participant.

 pid

    OpenVMS usage longword_unsigned
    type          longword (unsigned)
    access        write only
    mechanism     by reference
    PID (process identifier) of the OpenVMS process associated with
    the specified participant-index. The pid argument is the address
    of an unsigned longword that receives this PID.