SS$_NORMAL         Positive answer.
    LIB$_NEGANS        Negative answer.
    UTIL$_QUIPRO       Quit processing.
    UTIL$_QUICONACT    Continue processing, but cease prompting.
    LIB$_INVARG        Invalid argument list (no prompt strings).
    SS$_ACCVIO         Access violation (on user routine address).

    Any unsuccessful return from RMS, SYS$ASSIGN, $QIOW, or from the
    user-supplied routine (other than RMS$_EOF).