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