Links in HTML documents
12.3.3 Links and search engines
Authors may use the LINK element to provide a variety of information to search engines, including:
- Links to alternate versions of a document, written in another human language.
- Links to alternate versions of a document, designed for different media, for instance a version especially suited for printing.
- Links to the starting page of a collection of documents.
The Alternate link relationship defines an alternate version of the document. Translations of a page can be identified by using REL=Alternate along with the HREFLANG attribute. Versions of the page tailored for specific media can be provided by combining REL=Alternate with the MEDIA attribute.
-- Anyway, since I don't see "nofollow" in your HTML I assume it's a dofollow link to an alternate document version.