I've labelled various categories as __HIDDENCAT__, and indeed they don't appear at the page bottom unless a user preference is enabled, but they do appear in the Special:Categories, where they clutter the display for casual users.
Topic on Project:Support desk
that's just the way special:categories work - it shows alk categories, hidden or not
Is there a way to change the the 'Categories:' link at the page bottom in the categories box to point to a curated list. Wikipedia itself points to a help page, not its presumably enormous Special:Categories, for example
(My site design has strong control of categories, strict rules on their use, and lots of DPL reports to segment them, with some categories flagging up missing data in templates)
Where the link goes is controlled by the page MediaWiki:pagecategorieslink on your wiki
Just what I wanted, thanks