As somebody involved in an effort to simultaneously (a) develop a lot of content, (b) develop a good categorization scheme for it, I've so far come to the following conclusions about the categories feature in MediaWiki:

1. It's far, far better than nothing. Please remember that I believe this as as I criticize it below.

2. It's far too much work to recategorize an existing, substantial body of articles. And in fact, it's even more work to rename a category, keeping the same articles under it.

Why is this so? Here's what conspires:

* You can't rename/redirect category pages. If I create a bunch of pages with [[Category:Foo]], and later I decide that the category should be called [[Category:Bar]], I can't just move [[Category:Foo]] to [[Category:Bar]]. I have to go to every single article in category Foo, and edit each one manually to have the new category.

* The software almost silently accepts categorizing pages under categories that don't exist (more precisely: whose category page is empty). The only indication one's done something wrong is the link color in the category-- which my users happily ignore. (Hell, even I have problems always looking to check if I got it right.) It would be nice if this behavior were customizable. (Yes, and the proverbial day that I have time, I might even try it myself-- it's not the motivation that I lack.)

* There is no way to batch recategorize pages. I can't go to a category index or similar page, check a set of pages, select a category name to move them to, and have them all be recategorized as such. I imagine such a feature could be less than trivial to get under the current implementation: it would require doing a text search-and-replace over the text of every article to be recategorized, is my guess.

Any tricks, conventions, practices, etc. that any of you have found to work around these problems (short of "get your categories right from day 1" or "run an open site edited by thousands of users in their idle time") is welcome.

-- Luis Casillas casillas@mercedsystems.com