Link to this page
The directive link to this page sets conditions and criteria when one should link to the page which contains it. It should be obvious from the page name what the link means, e.g. as of, on this page, and easy to use that name in a sentence. When used as an edit summary tag, it is a directive to other editors to help clarify what belongs on this page for purposes of simplifying other pages.
Essentially it creates a more flexible category scheme. All pages with such instructions are logged at this link. If a mediawiki category scheme is implemented, every page with a link to this page directive on it, should probably become a single category.