http://www.mnot.net/rss/tutorial/
http://www.feedvalidator.org/

o RDF Site Summary          (RSS) 1.0    (XML/RDF)
  http://web.resource.org/rss/1.0/
  <link rel="alternate" type="application/rss+xml"
    title="RSS/1.0" href="foo.rss">

o Rich Site Summary         (RSS) 0.9x   (XML-only)
  Really Simple Syndication (RSS) 2.0    (XML-only)
  http://blogs.law.harvard.edu/tech/rss

o RSS3
  http://www.rss3.org/main.html

o ATOM
  http://ietf.org/html.charters/atompub-charter.html
  http://ietf.org/rfc/rfc4287.txt
  http://www.atomenabled.org/developers/syndication/

  <link rel="alternate" type="application/atom+xml"
   title="ATOM" href="foo.atom">

   <?xml version="1.0" encoding="utf-8"?>
   <feed xmlns="http://www.w3.org/2005/Atom">
     <title>OpenPKG Security Advisories</title>
     <subtitle>List of all published OpenPKG Security Advisory documents</subtitle>
     <icon>http://meta.openpkg.org/canvas/canvas-favicon.png</icon>
     <logo>http://meta.openpkg.org/canvas/canvas-openpkg.png</logo>
     <link rel="self" href="http://www.openpkg.org/news/security/advisories/"/>
     <updated>2006-03-24T18:30:02Z</updated>
     <author>
       <name>OpenPKG Project</name>
       <email>openpkg@openpkg.org</email>
       <uri>http://www.openpkg.org</uri>
     </author>
     <id>http://www.openpkg.org/news/security.atom</id>
     <entry>
       <id>OpenPKG-SA-2005.026-lynx</id>
       <title>2005-12-03: Security Advisory OpenPKG-SA-2005.026-lynx</title>
       <link rel="via" href="http://www.openpkg.org/security/advisories/OpenPKG-SA-2005.026-lynx.html"/>
       <updated>2003-12-13T18:30:02Z</updated>
       <summary>command injection</summary>
     </entry>
   </feed>