Special:Badtitle/NS90:User talk:Looney Toons/BASEPAGENAME - why it's used and why it's useful :)

The magic word (built in template) returns the basepagename as the value, so even if you change a pagename, the page and any subpages will return the name of the root page wherever the magic word is placed.

Example/subpage with the magic word on it will return the word "Example", since that's the base pagename.

When used in the Category markup, that means no matter what the page is changed to, it will render the appropriate category for that page.

Basically, I used it for all the page creation templates since it hammers the chance of inappropriately tagged pages down to nearly zero, especially if the page name is changed.