In that case they should drop |rel="alternate"|, but never use |rel="alternate"| instead of |rel="about"|. It would only cause confusion if you make it interchangeable and it isn't necessary at all.
Sorry, what I actually meant by 'interchangeable' is that an entry element may contain 'alternate' and/or 'about' links, and not that
they can be used to express the same meaning.
The spec currently says:
atom:entry elements MUST contain at least one atom:link element with a rel attribute value of "alternate".
So my initial thought was to change it to:
atom:entry elements MUST contain at least one atom:link element with a rel attribute value of [either] "alternate" [or "about"].
But now I see that this clause should be removed altogether.
-- Anne van Kesteren <http://annevankesteren.nl/>