sep spec text - use of word "link"

Can anyone explain this?
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When the P3P HTTP header is used as an alternative, servers SHOULD:
 Reference a policy in response to any request:
P3P-compliant sites SHOULD include a link to a policy reference file for a
Webresource whenever possible
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Does this mean a link tag, or an <a href=""> for user experience only?

Thanks

Giles Hogben