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