[Wikidata-l] Meta header for asserting that a web page is about a Wikidata subject

Suppose I publish a web page about a notable person, building or other entity; and that the subject has a Wikidata entry.

What's the best meta header, to assert that the page is about the same subject as the Wikidata entry?

I'm thinking of something like:

<link rel="foo" href="https://www.wikidata.org/wiki/Q42">

or

<meta name="DC.bar" content="https://www.wikidata.org/wiki/Q42">

but what values of foo or bar?

Given the likely ubiquity of Wikidata in the near future, should we mint:

<link rel="wikidata"

or a more generic:

<link rel="datasource" ?

Are there any such headers already in the wild? Should Wikipedia articles and pages on sister projects include such headers?