If your Atom feed file fails the w3.org validator, you will get an error message explaining where the error is in your feed file. The tutorial exercise below shows you a good example.Try to validate the following Atom feed file:<?xml version="1.0" encoding="utf-8"?><feed xmlns="http://www.w3.org/2005/Atom"> <title>Webmaster GlobalGuideLine</title> <subtitle>A place to find information for Webmasters </subtitle> <link href="http://GlobalGuideLine.com/atom.xml"/> <id>http://GlobalGuideLine.com/</id> <updated>2005-07-13T18:30:02Z</updated> <author> <name>GlobalGuideLine.com</name> <email>noreply@GlobalGuideLine.com</email> </author> <entry> <title>Webmaster FAQ Collection</title> <link href="http://GlobalGuideLine.com/faq/"/> <id>http://GlobalGuideLine.com/faq/</id> <updated>2005-07-13T18:30:02Z</updated> <summary>A massive collection of FAQs for Webmasters. </summary> </entry></feed>You will get the following error message:line 2, column 3: Missing atom:link with rel="self" <feed xmlns="http://w