The Invoke $GETMSG System Service to Get Message Text routine
    calls the system service $GETMSG and returns a message string
    into destination-string using the semantics of the caller's
    string.

    Format

      LIB$SYS_GETMSG  message-id [,message-length]

                      ,destination-string [,flags]

                      [,unsigned-resultant-array]

1  –  Returns

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

2  –  Arguments

 message-id

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

    Message identification to be retrieved by LIB$SYS_GETMSG. The
    message-id argument contains the address of an unsigned longword
    integer that is this message identification.

 message-length

    OpenVMS usage:word_unsigned
    type:         word integer (unsigned)
    access:       write only
    mechanism:    by reference

    Number of characters written into destination-string, not
    counting padding in the case of a fixed-length string. The
    message-length argument contains the address of an unsigned word
    integer that is this number.

    If the input string is truncated to the size specified in the
    destination-string descriptor, message-length is set to this
    size. Therefore, message-length can always be used by the calling
    program to access a valid substring of destination-string.

 destination-string

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

    Destination string. The destination-string argument contains the
    address of a descriptor pointing to this destination string.
    LIB$SYS_GETMSG writes the message that has been returned by
    $GETMSG into destination-string.

 flags

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

    Four flag bits for message content. The flags argument is the
    address of an unsigned longword that contains these flag bits.
    The default value is a longword with bits 0 through 3 set to 1.
    The flags argument is passed to LIB$SYS_GETMSG by reference and
    changed to value for use by $GETMSG.

    The following table lists the bit numbers, their values, and
    corresponding descriptions:

    Bit  Value Description

    0    1     Include text of message.
         0     Do not include text of message.
    1    1     Include message identifier.
         0     Do not include message identifier.
    2    1     Include severity indicator.
         0     Do not include severity indicator.
    3    1     Include facility name.
         0     Do not include facility name.

 unsigned-resultant-array

    OpenVMS usage:unspecified
    type:         unspecified
    access:       write only
    mechanism:    by reference, array reference

    A 4-byte array to receive message-specific information. The
    unsigned-resultant-array argument contains the address of this
    array.

    The contents of this 4-byte array are as follows:

    Byte Contents

    0    Reserved
    1    Count of FAO arguments
    2    User value
    3    Reserved