The use of XHTML has some persuasive advantages over the use of HTML for the production of accessible online media, some of which are presented herein. As the popularity of the Web and the complexity of what is presented over the Web has grown, HTML has become increasingly limited. to alleviate this difficulty and to provide for future needs, XML, or "Extensible Markup Language" was developed by the XML Working Group of the W3C. To use XHTML, and therefore a mark-up language that is future-proofed, without having to make significant changes to resources and activities, developers simply follow the rules for producing correct HTML 4.1 and add an extra line to their resource that identifies it as being accessible to XML-using agents. This line includes information about how to find the online, machine-readable information about how to interpret the XML being used.
XHTML is useful particularly when user agents have work to do: to find alternative resources, to synchronise files such as caption and video files, or to transform
So the recommended way to go is to use XHTML. Doing this is relatively easy: XHTML is almost the same as HTML but has a different header. To convert resources from HTML to XHTML, Dave Raggett has developed a very useful tool called HTML-Tidy. This tool is available in a number of formats for all platforms. It is highly recommended.
http://www.oasis-open.org/cover/siteIndex.html#toc-applications sub section 12, has resources on most mark-up languages using XML as a base, including MathML, PhysML and MusicML.
Last updated: 8 March 2002