"Pro Web 2.0 Mashups: Remixing Data and Web Services"
apress.com/"/> indicates that the document is an ???alternate??? representation (that is, a feed) of the web page http://www.apress.com/. ??? indicates the location of this feed document. ??? The attribute type="html" in the elements indicates the use of entity-encoded HTML. Writing a simple feed as RSS 2.0 and Atom 1.0 sheds some light on how the two formats compare. For a more detailed analysis, see the following: http://en.wikipedia.org/wiki/Atom_%28standard%29#Atom_Compared_to_RSS_2.0 Finally, Atom 1.0 has an official RNG schema, defined in the appendix of RFC 4287: http://atompub.org/rfc4287.html#schema Extensions to RSS 2.0 and Atom 1.0 Extensions to RSS 2.0 and Atom 1.0 enable you to take advantage of the popular feed formats to be able to move information within the whole feed ecology while adding more information than is allowed in the simple base RSS or Atom vocabulary. You can insert foreign XML elements (ones that are not defined in the respective specifications) into RSS 2.0 and Atom 1.0 by using XML namespaces. That is, with a few exceptions in Atom 1.0,5 foreign tags are allowed as long as they are qualified in a namespace that is different from that of the base format. For RSS 2.0, that would mean the foreign tag would have to be placed in some namespace instead of having no namespace such as the core elements in RSS 2.