pid

    OpenVMS usage longword_unsigned
    type          longword (unsigned)
    access        read only
    mechanism     by reference
    PID (process identifier) of the OpenVMS process or subprocess
    whose participant index is to be obtained. The pid argument is
    the address of an unsigned longword that contains this PID.

 participant-index

    OpenVMS usage longword_unsigned
    type          longword (unsigned)
    access        write only
    mechanism     by reference
    Participant index of the process or subprocess associated with
    the specified OpenVMS PID. The participant-index argument is
    the address of an unsigned longword that receives this index.
    Participant-index is assigned by the PPL$ facility at process
    creation time and is unique for each participant.