Thread:Nigel Victor Swan/@comment-15681036-20140416135145/@comment-24380060-20140417181031

Well, it's a feature tat only admins/b-crats have access to. Basically, the tag allows you to put the coding of a MediaWiki page of the same title into the page. (Ex. Outer Science will add the coding from MediaWiki:Outer Science onto that page.)

You can't edit MediaWiki pages on your own; you need admin rights to be able to edit them. Alternatively, you can ask someone to add your coding to the page to make it work. I can't help you with that, since I'm kinda on hiatus at my grandparents' house until Easter. (I'll still try to log on when I can.)