Is XHTML really Xtensible?

Question

Is there any way (server- or client-side) that I can actually extend HTML to include new tags? For example, it would be cool if I could write something like a schema fragment that defined a blogpost, which contains a postname, a postauthor, a posttime, and a postcontent, and thereafter refer to blogpost in my HTML rather than resorting to the basic HTML div and p tags.

Answer 1

Sounds like HTML5 is right up your alley!

You can use elements like section to wrap up all your posts, and article for each post, plus basics like header, nav, and footer. There isn't fine grained elements like postauthor or posttime but you can provide other attributes to help define these.

Hmm, seems I spoke to soon, you can use this too:

<time pubdate datetime="2010-11-13T20:00+09:00">Posted Nov 13.</time>

Answer 2

That would be awesome. Here is an article explaining why it won't work. Basically, you can extend the markup. But HTML browsers won't know how to interpret your new tags.