HTML 5 and XHTML 2
http://www.ibm.com/developerworks/web/library/x-html5xhtml2.html?S_TACT=105AGX08&S_CMP=EDU

de Jonge, Adriaan
IBM
2007

Abstract:

While the intention of both HTML V5 and XHTML V2 is to improve on the existing versions, the approaches the developers chose to make those improvements is very different. And with differing philosophies come distinct results. For the first time in many years, the direction of upcoming browser versions is uncertain. Uncover the bigger picture behind the details of these two standards.