We tag questions, such as "Why does my PHP goof up?", but if I'm searching for problems caused by "Problems caused by mixed quotes" (for example), it's not an easy way to search backwards.
So I suggest we allow for answer authors to tag their questions so we can think about things jeopard style as well as the normal way.
Answer could have been tagged:
Doctype as the solution has nothing to do with JS, but the problem caused by that JS solution is related to Doctype, Dom, Rendering, etc...
Should the question be re-tagged doc-type? No, that doesn't make any sense, he's asking about a problem he had making the jQueryUI working.