This may not be new to many of you, but I just discovered last week while reading The WHATWG Blog that the folks at HTML5 are planning to use the XHTML namespace. My first thought was “What?!”
The article linked to a mailing list post by Lachlan Hunt about why XHTML2 can’t use the XHTML namespace anyway :
But XHTML2 also has several major incompatibilities with XHTML1, which would effectively make it impossible to implement both XHTML 1.x and 2 in the same implementation, if they share the same namespace. XHTML 5, on the other hand, has not only been designed with compatibility in mind, success is dependent upon continuing to use the same namespace.
Basically, the only solution to this issue that should be considered is that we continue using the namespace and the XHTML2 WG use a different namespace.
It took much reading before I finally came to a post by Hunt in June 2007 that explained how HTML 5 is an extension of XHTML:
The fact is, whether the XHTML2 WG likes it or not, we are creating a revision of XHTML by extending XHTML 1.x. Therefore, it is correct for it to be called XHTML.
Although it still seems weird that HTML 5 was designed with compatibility in mind, but compatibility with XHTML rather than previous versions of HTML, I’m about ready to let it pass for a while as the back of my mind slowly tries to comprehend this. Maybe they’ll put out a much better explanation whenever it is that HTML 5 is finally ready for consumption.