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

 status-code

    Defines a longword (integer) value or expression equivalent to
    an integer value that gives the exit status of the subroutine by
    defining a numeric value for the reserved global symbol $STATUS.
    The value can be tested by the next outer command level. The low-
    order 3 bits of the longword integer value change the value of
    the reserved global symbol $SEVERITY. If you specify a status
    code, DCL interprets the code as a condition code. Note that
    even numeric values produce warning, error, and fatal error
    messages, and that odd numeric values produce either no message
    or a success or informational message.

    If you do not specify a status code, the current value of $STATUS
    is saved. When control returns to the outer command level,
    $STATUS contains the status of the most recently executed command
    or program.