anchor.diff:    (:select 41)
     (:print 42)
     (:execute 43)
  -  (:snapshot 44)
  +  (:snapshot 44) ;; printscreen
     (:insert 45)
     (:delete 46)
     (:help 47)
  
positive.code:   :f24
    (:numlock #x90)
    :scroll
    (:shift-l #xA0)
    :shift-r
    :control-l
  
negative.code:   :maunch-media-select
    :launch-app1
    :launch-app2
    (:oem1 #xba) ;; varies, ";:" on us
    :oem-plus
    :oem-comma
    :oem-minus
  