From: mco333@sympatico.ca   
      
   May be you are after an error recovery procedure.   
   If so, then   
      
     X : Y   
       | U   
       | error    
       ;   
      
   will do the job. This does not negate the productions,   
   but  is executed if X does not match Y or U.   
      
   This is documented in the Bison documentation.   
   eg:   
   http://www.slac.stanford.edu/comp/unix/gnu-info/bison_9.html   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)