Search value substitution
From semantic-mediawiki.org
Arbitrary templates and variables can be used in a query. An example is a selection criteria that displays all future events based on the current date:
[[Category:Event]]
[[end date::>{{CURRENTYEAR}}-{{CURRENTMONTH}}-{{CURRENTDAY}}]]
Another particularly useful variable for inline queries is {{FULLPAGENAME}} for the current page with namespace, which allows you to reuse a generic query on many pages. For an example of this, see Property:Population.
Read about inline queries for more information.
