display-id

    OpenVMS usage:identifier
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference

    Display identifier of the virtual display with which the
    subprocess is associated. The display-id argument is the address
    of an unsigned longword containing this identifier.

 command-desc

    OpenVMS usage:char_string
    type:         character string
    access:       read only
    mechanism:    by descriptor

    Command string. The command-desc argument is the address of a
    descriptor pointing to the command string.

 flags

    OpenVMS usage:mask_longword
    type:         longword (unsigned)
    access:       read only
    mechanism:    by reference

    Optional bit mask that specifies optional behavior. The flags
    argument is the address of an unsigned longword that contains the
    flag. The valid values for flags are as follows:

    SMG$M_DATA_FOLLOWS   Input data follows. The next call to
                         SMG$EXECUTE_COMMAND contains input data
                         for the currently executing command. Do not
                         specify this value if this is the last input
                         data item. If you do specify this value,
                         ret-status is not returned.
    SMG$M_SEND_EOF       Send end-of-file marker. The end-of-file
                         marker is sent to the subprocess.

 ret-status

    OpenVMS usage:cond_value
    type:         longword (unsigned)
    access:       write only
    mechanism:    by reference

    Optional status of the executed command, provided that the
    commands are not being buffered. The ret-status argument is the
    address of an unsigned longword containing this status.