Add 'visual-described' to subtitles xmltv.dtd

xmltv.dtd

@@ -586,13 +586,22 @@ stuff.
 
 <!-- Subtitles.  These can be either 'teletext' (sent digitally, and
 displayed at the viewer's request), 'onscreen' (superimposed on the
-picture and impossible to get rid of), or 'deaf-signed' (in-vision
-signing for users of sign language). You can have multiple subtitle
-streams to handle different languages.  Language for subtitles is
-specified in the same way as for programmes.
+picture and impossible to get rid of), 'deaf-signed' (in-vision
+signing for users of sign language) and 'visual-described' which
+means that the visuals are described and can be included in the
+presentation audio (how it is selected for presentation is market
+dependent).  Note that Visual-described is also known as DVS
+(Descriptive Video Service, or Descriptive (or Described) Video,
+or Video Description, or Visual Description or Audio Described,
+again, depending on market. You can have multiple subtitle streams
+to handle different languages.  Language for subtitles is specified
+in the same way as for programmes.
 -->
 <!ELEMENT subtitles (language?)>
-<!ATTLIST subtitles type (teletext | onscreen | deaf-signed) #IMPLIED>
+<!ATTLIST subtitles type (teletext |
+			  onscreen |
+			  deaf-signed |
+			  visual-described) #IMPLIED>
 
 <!-- Rating.  Various bodies decide on classifications for films -
 usually a minimum age you must be to see it.  In principle the same