Board Thread:Support Requests - Getting Technical/@comment-15636815-20151104192405/@comment-1757994-20151104232208

Whitelisting means you can edit those pages or create those pages on any wiki where you're an admin. If the pages don't exist on a wiki, however, you won't see them on a list of pages that exist on that wiki. Would that be "obvious" enough for you?

In the MediaWiki: space, if some pages don't exist, MediaWiki supplies some default hard-coded content (e.g., MediaWiki:Common.css, to name one).