xhtml modules, how to use, and the x/html 5 stanard?

[wgabrie]

I really don't know where this goes, but, xhtml is said to be a great thing because of its "plug-in" modules. But, how does anyone even use xhtml modules? I have searched the internet and found little information.

The w3schools.org site provides lists of modules and if you go to the w3.org site the doctypes to use them are listed somewhere. However, the special module doctypes only have a few tags so it really invalidates every other tag on the page even if it was standards xhtml before. So, why would I use the doctype to begin with?

How could I use the Target Module in xhtml 1.0 strict or xhtml 1.1 without using a doctype? Also, how could modules be plugged into the x/html 5 standard? Why would or wouldn't that be possible?

[zcorpan]

Modules in this case are actually just a bunch of DTDs that can be combined to form a custom schema. You don't need DTDs at all in order to use a feature. It also is not something that can only be done with XHTML -- you could write SGML DTDs in a modular way too if you want.

If you want to write a custom schema for (X)HTML5 then you're probably better off forking the one Validator.nu uses, which is also split up into modules. You can find it on http://syntax.whattf.org/ .