anchor.diff:            remove-property
             put-attribute
             insert-string-with-attribute
  -          after-property
  -          before-property
             following-property
             preceding-property
             forward-search-property-end
  
positive.code:       (when killp
          (kill-push string))
        t)))
  
  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  
negative.code:   (let ((start (current-point)))
      (insert-string string)
      (put-attribute start (current-point) attribute)))
  
  (defun following-property (property-name)
    (%syntax-pos-property (current-charpos) property-name))
  