anchor.diff:      (:time :datetime)
       (:track :kind :src :srclang :label :default)
       (:video :autoplay :preload :controls :loop :poster :height :width
  -     :mediagroup :muted :src))
  +     :mediagroup :muted :src :crossorigin))
     "Alist of (tag . attributes). These are the element-specific
   attributes, beyond the global attributes.")
   
  
positive.code:     (:html :manifest)
      (:iframe :src :srcdoc :name :width :height :sandbox :seamless)
      (:img :src :alt :height :width :usemap :ismap :border :crossorigin
       :srcset :sizes)
      (:input :name :disabled :form :type :maxlength :readonly :size :value
       :autocomplete :autofocus :list :pattern :required :placeholder
       :dirname :checked :multiple :src :height :width
  
negative.code:     (:param :name :value)
      (:progress :value :max)
      (:q :cite)
      (:script :type :language :src :defer :async :charset :language :integrity
       :crossorigin)
      (:select :name :disabled :form :size :multiple :autofocus :required)
      (:source :src :srcset :sizes :type :media)
      (:style :type :media :scoped)
  