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Alternatively, or additionally, I could make the millennium category only appear on the century categories if it exists. So, once the millennium category is deleted, the redlink for it would disappear from the bottom of the century category pages. They might need a null edit to make that happen, though. I have a preference for the first way I have done it – so that the millennium category will appear on the century page if the parameter is used. – FayenaticLondon 21:59, 27 January 2016 (UTC)