NAME
        CheckRexxMsg - Check if a rexxmsg is from arexx

   SYNOPSIS
        result = CheckRexxMsg(message)
        D0                    A0

        bool checkrexxmsg(struct rexxmsg *);

   FUNCTION
        This function checks to make sure that the message is from ARexx
        directly.  It is required when using the Rexx Variable Interface
        routines (RVI) that the message be from ARexx.

        While this function is new in the V37 amiga.lib, it is safe to
        call it in all versions of the operating system.  It is also
        PURE code, thus usable in resident/pure executables.

   NOTE
        This is a stub in amiga.lib.  It is only available via amiga.lib.
        The stub has two labels.  One, _CheckRexxMsg, takes the arguments
        from the stack.  The other, CheckRexxMsg, takes the arguments in
        registers.

   EXAMPLE
        if (CheckRexxMsg(rxmsg))
        {
                /* message is one from arexx */
        }

   INPUTS
        message         A pointer to the rexxmsg in question

   RESULTS
        result          A boolean - TRUE if message is from ARexx.

   SEE ALSO
        getrexxvar(), setrexxvar()