anchor.diff:       :tags (:binary :video :audio-video-interleave)
        :mime ("video" "x-msvideo"))
       (("mpeg" "mpg" "mpe" "mp4")
  -     :tags (:binary :video)
  +     :tags (:binary :video :mpeg)
        :mime ("video" "mpeg"))
       (("mp4")
        :tags (:mpeg-4)
  -     :mime ("video" "mp4")))
  +     :mime ("video" "mp4"))
  +    (("webm")
  +     :tags (:binary :video :webm)
  +     :mime ("video" "webm")))
     "List of known file extensions and associated tags.")
  
positive.code:     (("man" "1" "2" "3" "4" "5" "6" "7" "8" "9")
       :tags (:text :troff :manual-page)
       :mime ("application" "x-troff-man"))
      ;; Source code
      (("c" "h")
       :tags (:text :c)
  
negative.code:      :tags (:binary :audio :audio-interchange)
       :mime ("audio" "x-aiff"))
      (("mpga" "mpega" "mp2" "mp3" "m4a")
       :tags (:binary :audio :mpeg)
       :mime ("audio" "mpeg"))
      (("mp3")
       :tags (:mpeg-3))
  