anchor.diff:     (low-mark :reader low-mark)
      (high-mark :reader high-mark)
      (modified :initform nil :reader modified-p))
  -  (:documentation "The Drei standard buffer [an instantable subclass of buffer]."))
  +  (:documentation "The standard instantiable class for buffers."))
   
   (defgeneric buffer (mark)
     (:documentation "Return the buffer that the mark is positioned in."))  
   
   (defclass mark () ()
  -  (:documentation "A base class for all marks."))
  +  (:documentation "The base class for all marks."))
   
   (defclass left-sticky-mark (mark) ()
  -  (:documentation "A subclass of mark.  A mark of this type will \"stick\" to the left of 
  -an object, i.e. when an object is inserted at this mark, the mark will 
  -be positioned to the left of the object"))
  +  (:documentation "A subclass of mark.  A mark of this type will
  +\"stick\" to the left of an object, i.e. when an object is
  +inserted at this mark, the mark will be positioned to the left of
  +the object."))
   
   (defclass right-sticky-mark (mark) ()
  -  (:documentation "A subclass of mark.  A mark of this type will \"stick\" to the right of 
  -an object, i.e. when an object is inserted at this mark, the mark will 
  -be positioned to the right of the object."))
  +  (:documentation "A subclass of mark.  A mark of this type will
  +\"stick\" to the right of an object, i.e. when an object is
  +inserted at this mark, the mark will be positioned to the right
  +of the object."))
   
   (defgeneric offset (mark)
     (:documentation "Return the offset of the mark into the buffer."))
   
   (defgeneric (setf offset) (new-offset mark)
  -  (:documentation "Set the offset of the mark into the buffer.  A no-such-offset
  -condition is signaled if the offset is less than zero or greater than
  -the size of the buffer."))
  +  (:documentation "Set the offset of the mark into the buffer.  A
  +no-such-offset condition is signaled if the offset is less than
  +zero or greater than the size of the buffer."))
   
   (defclass mark-mixin ()
     ((buffer :initarg :buffer :reader buffer)
  
positive.code:   ((offset :reader condition-offset :initarg :offset))
    (:report (lambda (condition stream)
  	     (format stream "No such offset: ~a" (condition-offset condition))))
    (:documentation "This condition is signaled whenever an attempt is
  made to access buffer contents that is before the beginning or after
  the end of the buffer."))
  
  (define-condition offset-before-beginning (no-such-offset)
    ()
  
negative.code: (in-package :drei-buffer)
  
  (defclass buffer () ()
    (:documentation "The base class for all buffers. A buffer conceptually contains a
  large array of arbitrary objects.  Lines of objects are separated by
  newline characters.  The last object of the buffer is not
  necessarily a newline character."))
  