Thread:Project:Support desk/How to check from a template if a page is in a given category?/reply (4)

Not yet, but that would probably make a good feature for that extension.

(Basically PageInCat can only detect if the current page is in a category. It can't detect if an arbitrary page is in some category)

However, even if PageInCat did support Micru's request, the extension is not installed on Wikimedia, so can't be used on wikisource.