anchor.diff:  ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ILST ATOMS ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
   (defclass atom-ilst (mp4-container-atom) ())
   
  -;; (defmethod initialize-instance :around ((me atom-ilst) &key mp4-file  &allow-other-keys)
  -;;   "Construct an ilst atom.  ILST atoms are containers that hold data elements related to tagging.
  -;; Loop through this container and construct constituent atoms"
  -;;   (declare #.utils:*standard-optimize-settings*)
  -;;   (with-mp4-atom-slots (me)
  -;;     (call-next-method)))
  -
   (defclass atom-©alb (atom-ilst) ())
   (defclass atom-aART (atom-ilst) ())
   (defclass atom-©art (atom-ilst) ())
  
positive.code:                                +itunes-genre-x+ +itunes-lyrics+ +itunes-purchased-date+
                                 +itunes-title+ +itunes-tool+ +itunes-writer+))
                   (stream-read-utf-8-string-with-len mp4-file (- (atom-size me) 16)))
                  ((member (atom-type parent)
                           (list +itunes-track+
                                 +itunes-track-n+
  
negative.code: (defconstant +itunes-disk+           (mk-mp4-atom-type #\d  #\i #\s #\k) "octets: disk number, can be n of N")
  (defconstant +itunes-encoder+        (mk-mp4-atom-type #xa9 #\e #\n #\c) "text: who encoded")
  (defconstant +itunes-genre+          (mk-mp4-atom-type #\g  #\n #\r #\e) "octets: genre of file")
  (defconstant +itunes-genre-x+        (mk-mp4-atom-type #xa9 #\g #\e #\n) "text: yet another genre atom")
  (defconstant +itunes-groups+         (mk-mp4-atom-type #xa9 #\g #\r #\p) "text: ???")
  (defconstant +itunes-lyrics+         (mk-mp4-atom-type #xa9 #\l #\y #\r) "text: lyrics tag")
  (defconstant +itunes-purchased-date+ (mk-mp4-atom-type #\p  #\u #\r #\d) "text: when song was purchased")
  