Last modified: 2011-03-09 21:14:51 UTC
Step : set category "Cat" is article "Foo" edit category "Cat" and save remove category "Cat" from article "Foo" now that category "Cat" does not contain any article, you can't see it in Special:Categories.
May be should I ask in a different way : is there a simple way to access to easily to Categories with no Articles. Because they can cause some trouble. Example : I create a mispelled category. Then I create the correct one. I recat all the page to the correct one. From now on, you can't see the mispelled category in Special:Categories (because she is empty) But the mispelled still exists and could *inadvertently* use the misspelled one and trust it is the good one without brother. Now that the number of categories become huge, such a thing could happen more often.
Fixed by adding a Special:Unusedcategories that will list categories not referenced anywhere.