Category is category metadata for Feeds and Entries.

Content either contains or links to the content of the entry.

Entry is an Atom Entry.

Feed is an Atom Feed.

Generator identifies the agent used to generate a feed, for debugging and other purposes.

Link is an Atom link that defines a reference from an entry or feed to a Web resource.

Parser is an Atom Parser.

Person represents a person in an Atom feed for things like Authors, Contributors, etc.

Source contains the feed information for another feed if a given entry came from that feed.