efn

    OpenVMS usage:ef_number
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Number of the event flag to be set when the $GETSYI request
    completes. The efn argument is a longword containing this number;
    however, $GETSYI uses only the low-order byte.

    Upon request initiation, $GETSYI clears the specified event
    flag (or event flag 0 if efn was not specified). Then, when the
    request completes, the specified event flag (or event flag 0) is
    set.

    HP strongly recommends the use of the EFN$C_ENF "no event flag"
    value as the event flag if you are not using an event flag to
    externally synchronize with the completion of this system service
    call. The $EFNDEF macro defines EFN$C_ENF. For more information,
    see the HP OpenVMS Programming Concepts Manual.

 csidadr

    OpenVMS usage:process_id
    type:         longword (unsigned)
    access:       modify
    mechanism:    by 32- or 64-bit reference
    OpenVMS Cluster system identification of the node about which
    $GETSYI is to return information. The csidadr argument is the 32-
    or 64-bit address of a longword containing this identification
    value.

    The cluster-connection software assigns the OpenVMS Cluster
    system identification of a node. You can obtain this information
    by using the DCL command SHOW CLUSTER. The value of the cluster
    system identification for a node is not permanent; a new value is
    assigned to a node whenever it joins or rejoins the cluster.

    You can also specify a node to $GETSYI by using the nodename
    argument. If you specify csidadr, you need not specify nodename,
    and vice versa. If you specify both, they must identify the
    same node. If you specify neither argument, $GETSYI returns
    information about the local node; however, for wildcard
    operations, you must use the csidadr argument.

    If you specify csidadr as -1, $GETSYI assumes a wildcard
    operation and returns the requested information for each node in
    the cluster, one node per call. In this case, the program should
    test for the condition value SS$_NOMORENODE after each call to
    $GETSYI and should stop calling $GETSYI when SS$_NOMORENODE is
    returned.

 nodename

    OpenVMS usage:process_name
    type:         character-coded text string
    access:       read only
    mechanism:    by 32- or 64-bit descriptor-fixed-length string
                  descriptor
    Name of the node about which $GETSYI is to return information.
    The nodename argument is the 32- or 64-bit address of a character
    string descriptor pointing to this name string.

    The node name string must contain from 1 to 15 characters and
    must correspond exactly to the node name; no trailing blanks or
    abbreviations are permitted.

    You can also specify a node to $GETSYI by using the csidadr
    argument. See the description of csidadr.

 itmlst

    OpenVMS usage:32-bit item_list_3 or 64-bit item_list_64b
    type:         longword (unsigned) for 32-bit; quadword (unsigned)
                  for 64-bit
    access:       read only
    mechanism:    by 32- or 64-bit reference
    Item list specifying which information is to be returned about
    the node or nodes. The itmlst argument is the 32- or 64-bit
    address of a list of item descriptors, each of which describes an
    item of information. An item list in 32-bit format is terminated
    by a longword of 0; an item list in 64-bit format is terminated
    by a quadword of 0. All items in an item list must be of the same
    format-either 32-bit or 64-bit.

    To view the item code diagrams and descriptor fields tables, see
    the HP OpenVMS System Services Reference Manual.

 iosb

    OpenVMS usage:io_status_block
    type:         quadword (unsigned)
    access:       write only
    mechanism:    by 32- or 64-bit reference
    I/O status block to receive the final completion status. The
    iosb argument is or the 32- or 64-bit address of the quadword I/O
    status block.

    When you specify the iosb argument, $GETSYI sets the quadword to
    0 upon request initiation. Upon request completion, a condition
    value is returned to the first longword; the second longword is
    reserved for future use.

    Though this argument is optional, HP strongly recommends that you
    specify it, for the following reasons:

    o  If you are using an event flag to signal the completion of
       the service, you can test the I/O status block for a condition
       value to be sure that the event flag was not set by an event
       other than service completion.

    o  If you are using the $SYNCH service to synchronize completion
       of the service, the I/O status block is a required argument
       for $SYNCH.

    o  The condition value returned in R0 and the condition value
       returned in the I/O status block provide information about
       different aspects of the call to the $GETSYI service. The
       condition value returned in R0 gives you information about the
       success or failure of the service call itself; the condition
       value returned in the I/O status block gives you information
       about the success or failure of the service operation.
       Therefore, to accurately assess the success or failure of the
       call to $GETSYI, you must check the condition values returned
       in both R0 and the I/O status block.

 astadr

    OpenVMS usage:ast_procedure
    type:         procedure value
    access:       call without stack unwinding
    mechanism:    by 32- or 64-bit reference
    AST service routine to be executed when $GETSYI completes. The
    astadr argument is the 32- or 64-bit address of this routine.

    If you specify astadr, the AST routine executes at the same
    access mode as the caller of the $GETSYI service.

 astprm

    OpenVMS usage:user_arg
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    AST parameter to be passed to the AST service routine specified
    by the astadr argument. The astprm argument is the longword
    parameter.