NAME
        IsRexxMsg - Function to determine if a message came from ARexx

    SYNOPSIS
        result = IsRexxMsg(msgptr)
        D0                 A0

        bool isrexxmsg(struct rexxmsg *);

    FUNCTION
        This function can be used to determine if a message came from an
        ARexx program.

    INPUTS
        msgptr - A pointer to the suspected rexxmsg.

    RESULTS
        result - A boolean:  TRUE if it is an ARexx message, FALSE if not.

    SEE ALSO
        createrexxmsg()

    BUGS