anchor.diff:  
   (defclass parse-tree ()
     ((start-mark :initform nil :initarg :start-mark :reader start-mark)
  -   (size :initform nil :initarg :size)))
  -
  -(defgeneric start-offset (parse-tree))
  +   (size :initform nil :initarg :size))
  +  (:documentation "The base class for all parse trees."))
  +
  +(defgeneric start-offset (parse-tree)
  +  (:documentation "The offset in the buffer of the first
  +character of a parse tree."))
   
   (defmethod start-offset ((tree parse-tree))
     (let ((mark (start-mark tree)))
  
positive.code: 
  
  (defmacro grammar (&body body)
    (let ((rule (gensym "RULE"))
  	(rules (gensym "RULES"))
  	(result (gensym "RESULT")))
  
negative.code:                   :initform (error "A command table has not been provided for this syntax")
                    :reader command-table)
     (%cursor-positions :accessor cursor-positions
                        :initform nil))
    (:documentation "The base class for all syntaxes."))
  
  (defun syntaxp (object)
    "Return T if `object' is an instance of a syntax, NIL
  