4.1.1 "The "atom:feed" element is the document (i.e., top-level) element of an Atom Feed Document, acting as a container for metadata and data associated with the feed. Its element children consist of one or more metadata elements followed by zero or more atom:entry child elements."
A little nit-picky, but it looks like a minimum of three metadata elements are required: link, title and updated.
4.2.8 The "atom:image" Element
There was some support for the idea of changing the name of atom:image to atom:logo. Is there any opposition to that?
