This note describes how wikilinks to and within Wikidata could be written.
Within Wikidata edit
[[Q42]]links to the item Q42[[en:Berlin]]is not a language link but links internally to the item that is linked to the English Wikipedia article on Berlin[[enwiki:Berlin]]is a link to the English Wikipedia article on Berlin
Within Wikipedia edit
[[wikidata:Q42]]links to the item Q42 on Wikidata[[data:en:Berlin]]links to the item that is linked to the English Wikipedia article on Berlin[[wikidata:User:Foo]]links to the page with the title User:Foo on Wikidata