anchor.diff:  	    (report-ambiguity session pre-index max-index alternative-results)))
   	(setf (parse-session-results session)
   	  (append alternative-results (parse-session-results session)))))
  -    (values max-index prior-post-index reported-gap?)))
  +    (values max-index prior-post-index))) ;  reported-gap?
   
   (defun report-gap (session start end)
     (let ((locations (parse-session-locations session))
  
positive.code:     (when (> max-index (+ pre-index min-size))
        ;;
        (unless (= prior-post-index pre-index) 
  	(when (report-gap session prior-post-index pre-index)
  	  (setq reported-gap? t)))
        (setq prior-post-index max-index)
        ;;
        (let ((alternative-results nil))
  
negative.code: 	(toplevel-count   0)
  	(toplevel-rule  (parser-toplevel-rule (parse-session-parser session)))
  	(locations      (parse-session-locations session))
  	;; (reported-gap?  nil)
  	)
      (dolist (node (parser-location-post-nodes loc))
        (let ((post-index (parser-node-post-index node)))
  	(cond ((> post-index max-index)
  