Require either an alternate link or an id as children of atom:feed elements.
In atompub-format-07, change one bullet in section 4.1.1.
atom:feed elements MUST contain at least one atom:link element with a relation of "alternate".
atom:feed elements that contain no child atom:id element MUST contain at least one atom:link element with a relation of "alternate".
Tools which expect feed level links (such as Bloglines) will need to be prepared for the absense of this information.
see also: PaceFeedIdOrSelf