stream

    OpenVMS usage:longword_unsigned
    type:         longword (unsigned)
    access:       write only
    mechanism:    by reference
    Stream number specifying the stream to which the message refers.
    The stream argument is the address of a longword into which the
    job controller writes the number of the stream referred to by
    the message. In single-threaded symbionts, the stream number is
    always 0.

 buffer

    OpenVMS usage:char_string
    type:         character string
    access:       write only
    mechanism:    by descriptor
    Address of the descriptor that points to the buffer into which
    the job controller writes the message. SMB$READ_MESSAGE uses
    the Run-Time Library string-handling (STR$) routines to copy
    the message into the buffer you supply. The buffer should be
    specified by a dynamic string descriptor.

 request

    OpenVMS usage:identifier
    type:         longword (unsigned)
    access:       write only
    mechanism:    by reference
    Code that identifies the request. The request argument is the
    address of a longword into which SMB$READ_MESSAGE writes the code
    that identifies the request.

    There are seven request codes. Each code is interpreted as a
    message by the symbiont. The codes and their descriptions follow:

    SMBMSG$K_START_       Initiates processing on an inactive
    STREAM                symbiont stream. The job controller sends
                          this message when a START/QUEUE or an
                          INITIALIZE/QUEUE/START command is issued
                          on a stopped queue.
    SMBMSG$K_STOP_        Stops processing on a started queue. The
    STREAM                job controller sends this message when a
                          STOP/QUEUE/NEXT command is issued, after
                          the symbiont completes any currently active
                          task.
    SMBMSG$K_RESET_       Aborts all processing on a started stream
    STREAM                and requeues the current job. The job
                          controller sends this message when a
                          STOP/QUEUE/RESET command is issued.
    SMBMSG$K_START_TASK   Requests that the symbiont begin processing
                          a task. The job controller sends this
                          message when a file is pending on an idle,
                          started queue.
    SMBMSG$K_STOP_TASK    Requests that the symbiont abort the
                          processing of a task. The job controller
                          sends this message when a STOP/QUEUE/ABORT
                          or STOP/QUEUE/REQUEUE command is issued.
                          The item SMBMSG$K_STOP_CONDITION identifies
                          whether this is an abort or a requeue
                          request.
    SMBMSG$K_PAUSE_TASK   Requests that the symbiont pause in the
                          processing of a task but retain the
                          resources necessary to continue. The
                          job controller sends this message when
                          a STOP/QUEUE command is issued without
                          the /ABORT, /ENTRY, /REQUEUE, or /NEXT
                          qualifier for a queue that is currently
                          printing a job.
    SMBMSG$K_RESUME_      Requests that the symbiont continue
    TASK                  processing a task that has been stopped
                          with a PAUSE_TASK request. This message is
                          sent when a START/QUEUE command is issued
                          for a queue served by a symbiont that has
                          paused in processing the current task.