alternate Links to an alternate version of the document (i.e. print page, translated or mirror)
author Links to the author of the document
bookmark Permanent URL used for bookmarking
help Links to a help document
license Links to copyright information for the document
next The next document in a selection
nofollow Links to an unendorsed document, like a paid link.\n("nofollow" is used by Google, to specify that the Google search spider should not follow that link)
noreferrer Specifies that the browser should not send a HTTP referer header if the user follows the hyperlink
prefetch Specifies that the target document should be cached
prev The previous document in a selection
search Links to a search tool for the document
tag A tag (keyword) for the current document