Template:Mediawiki

This template links to a page on from the Help pages. The template has two parameters:
 * 1) Pagename, optionally preceded by an interwiki link prefix valid on mediawiki.org
 * 2) (optional) Link description

Spaces in Page Titles
These must be replaced with underscores, otherwise the urlencoding mangles them and you get a page not found error on mediawiki.org.

So need not

Demo of interwiki link
gives either Help:Calculation or Help:Calculation, rendered as Help:Calculation or Help:Calculation, respectively.