anchor.diff:   
   ;;; Generic block formatting
  -(defclass block-output-record-mixn ()
  +(defclass block-output-record-mixin ()
     ()
     (:documentation "The class representing one-dimensional blocks of cells."))
   
  -(defmethod replay-output-record ((bl block-output-record-mixn) stream
  +(defmethod replay-output-record ((bl block-output-record-mixin) stream
                                    &optional region (x-offset 0) (y-offset 0))
     (when (null region)
       (setq region (or (pane-viewport-region stream) +everywhere+)))
  
positive.code: 
  ;;; STANDARD-COLUMN-OUTPUT-RECORD class
  (defclass standard-column-output-record (column-output-record
                                           block-output-record-mixn
                                           standard-sequence-output-record)
    ())
  
  
negative.code: (defgeneric adjust-item-list-cells (item-list-record stream))
  
  (defclass standard-item-list-output-record (item-list-output-record
                                              block-output-record-mixin
                                              standard-sequence-output-record)
    ((x-spacing :initarg :x-spacing)
     (y-spacing :initarg :y-spacing)
  