VMS Help RMS, $WAIT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    The Wait service suspends image execution until an asynchronous
    file or record service completes. The same control block that
    is used with the asynchronous file or record service call is
    specified as the parameter for the Wait service. If it is an
    asynchronous file service, the control block is a FAB; if it is
    an asynchronous record service, the control block is a RAB. Upon
    completion of the service, RMS returns control to your program at
    the point following the Wait service call.

                         RAB64 USERS (ALPHA ONLY)

       On Alpha systems, RAB64 can replace the RAB or RAB prefix
       wherever it is used with the Wait service on OpenVMS Alpha
       systems.

    Format

      SYS$WAIT  control-block

1 - Returns

    OpenVMS usage:cond_value
    type:         longword
    access:       write only
    mechanism:    by value

    The value is returned in symbolic offset FAB$L_STS or RAB$L_STS.
    Symbolic offset FAB$L_STV or RAB$L_STV may contain additional
    status information.

2 - Argument

 control-block

    type:
    access:
    mechanism:    0

 fab or rab

    OpenVMS usage:fab or rab
    type:         longword (unsigned)
    access:       modify
    mechanism:    by reference

    FAB or RAB control block whose contents are to be used as
    indirect arguments for the Open service call. The fab or rab
    argument is the address of the FAB or RAB control block.

3 - Condition Values Returned

 The following condition values can be returned. Use the Help Message
 utility to access online message descriptions.

    The RMS completion status codes for the Wait service are
    determined by the service being awaited, unless the address of
    the FAB or RAB specified for the wait is different from that
    specified for the awaited operation. In this case, RMS$_NORMAL is
    returned.