Special Flags %trace-on% and %trace-off%

The special tracing flags %trace-on% and %trace-off% are predefined and have the effect of temporarily turning all tracing on and off. They are used as all other local tracing flags, as shown in the following example:

          


((alt PASSIVE
	 (
	  ;; branch 1 of alt passive
	  ((verb ((voice passive)))
	   (prot none))


;; branch 2 of alt passive
	  ((verb ((voice passive)))


%trace-off%          ;; Turn off tracing of details in this branch


(prot any)
	   (prot ((cat np)))
	   (by-obj ((cat pp) (prep ((lex `by'))) (np (^ prot))))
	   (pattern (dots verb by-obj dots))


%trace-on%           ;; Turn tracing back on


)))


;; body of alt passive (common to all branches)
	(verb ((cat verb-group)))
	...)


          
          

%Trace-off% is generally used to remove tracing information from a region of the grammar that has already been debugged but still leaving the alt traversal tracing messages on. The same effect is most of the time achieved by using the trace-level function, but %trace-off% allows finer tuning of the tracing behavior of FUF.