When Is it OK To Invent New Tags?. Tantek Çelik, smart Microsoft browser guy, is blogging from the big W3C meeting now going on in Boston. Among other things, he's mad because some W3C specifications are written not in HTML but in a completely different XML language called xmlspec, and that language has some tags that are a lot like HTML tags, so why don't we just use HTML tags? I'll address some of the historical background and specifics, but Tantek is pointing at a real important issue in the world of XML: when do you invent your own language, and when do you re-use someone else's? Warning: long, and loaded with markup design theory and obscure standards history.… [ongoing]

Tim Bray, an old XML-DEV collegue and a major living landmark in XML history, writes about inventing new tags.  I found it interesting because I am hacking together something that will allow anyone to invent new HTML tags with a few lines of Python on the client-side.  You want a <laugh> tag?  You got it.