Slide 9 of 25

to improve internationalization, support for UNICODE is now required by the HTML V4.0. support for languages with right to left text flow has been enhanced as well as the ability to include non-ASCII characters in URIs (but i would still strongly discourage URIs with non-ASCII characters).

there is actually more than one DTD (Document Type Definition) for HTML V4.0:

• strict: this excludes all the presentation attributes and elements that the W3C expects to be phased out ("depreciated" attributes and elements). this is the preferred DTD !
  see http://www.w3.org/TR/REC-html40/strict.dtd
  
  
• transitional or loose: these definitions still include all the depreciated attributes and element.
  see http://www.w3.org/TR/REC-html40/loose.dtd
  
  
• frameset: this is the definition to be used for documents which include frames.
  see http://www.w3.org/TR/REC-html40/frameset.dtd