Definition: There is exactly one Author of an Entry, and that Author is identified by a non-empty name and an optional URI of a person, organization, or system. Example:
<author> <name>Bob B. Bobbington</name> <url>http://bob.example.com/</url> <email>email@example.com</email> </author>
Homepage: The URL of author's home page.
Weblog: The URL of the author's weblog.
PGP key (part of Security?)
IP : IP of the Author or Contributor - Is important in Atom for Wikis