XHTML: The Extensible Hypertext Markup Language
A reformulation of HTML in XML with namespaces for HTML 4.0 strict, transitional and frameset DTDs
Modularises HTML for subsetting/combining with other tag-sets
Document Profiles provide basis for interoperability guarantees, complementing work on device profiles
Next generation forms - designed form the ground up for platform portability and an improved match to database and workflow applications