Unregistered link relationship: foo
The current values for the Registry of Atom Link Relations are as follows:
alternatecurrentenclosureeditedit-mediafirstlastlicensenextnext-archivepaymentprev-archivepreviousrelatedrepliesselfserviceupviaChange the attribute value to one in the list.
If a value other than one of the above is desired, either register the relation with the IANA registry, or express the rel as a fully qualified URI.