Hi! Spreading the word about this one - I had to explain it to Looney Toons, too.
There are two different Magic Words that point to pages further up a category tree: BASEPAGENAME and ROOTPAGENAME. BASEPAGENAME returns the page name up to but not including the final slash, while ROOTPAGENAME returns the page name up to but not including the first slash. If you want to autoinclude the category for a particular work, you want ROOTPAGENAME, not BASEPAGENAME.
- Page = Babylon 5/Recap/Film (which I picked because we use both Magic Words in the footer)
- ROOTPAGENAME = Babylon 5
- BASEPAGENAME = Babylon 5/Recap