"guid element" - huh?

[BigAl75]

I followed the tutorials on W3schools and created an xml document for displaying my company's news via RSS. I went to http://www.feedvalidator.org to validate my feed, and it says:line 14, column 3: item should contain a guid element(the above 'error' is being caused by the </item> code in the xml)Not 100% sure what it is I'm doing wrong. It says "This feed is valid, but may cause problems for some users. We recommend fixing these problems." and I'd like to. As much time as I spent validating the XHTML and CSS for the over 100 pages on the site, I'd like to have this working 100% as well.Here's a sample of the xml sheet. Can anyone tell me what I need to fix?

<?xml version="1.0" encoding="iso-8859-1"?><?xml-stylesheet type="text/xsl" href="pmifeed.xsl"?>    <rss version="2.0">    <channel>			<title>Porous Materials, Inc.</title>			<link>http://www.pmiapp.com</link>			<description>Porous Materials, Inc. is the leading designer and manufacturer of custom scientific instruments for characterization of porosity, pore diameter, pore volume, pore surface area, liquid permeability, gas permeability, density, and integrity testing. PMI also provides consulting services to seek out solutions for characterization of porosity and analysis of porosity. The testing services division of PMI offers contract testing services for a wide variety of tests.</description>					<item>				<title>PMI Releases New Website</title>				<link>http://www.pmiapp.com/news/index.html#website</link>				<description>Porous Materials, Inc. is proud to release a new look to our website. The new website is optimized for the web, with each page passing web standards. Our new design was made for all users in mind, and should load faster for our visitors who are still on dial-up.</description>			</item>						<item>				<title>PMI Goes Mobile</title>				<link>http://www.pmiapp.com/news/index.html#mobile</link>				<description>Porous Materials, Inc. is proud to announce the release of its newest website - PMI Mobile. Customers and other visitors can now browse a condensed version of this website on any mobile device with an internet connection</description>			</item>    </channel>    </rss>

[boen_robot]

As it says, the feed IS valid. This is only a warning (CSS like warning).If you look at the page that explains the RSS <item/> element you'll notice at the bottom a list of allowed contents in it, among which is the <guid/> element. The RSS validator reccomends you have one in every item so that it could be identified regarless of title. Even without it though, the feed is valid and completely usable as well as forwards compatable.

[BigAl75]

Yeah, I know it's valid, but I'd rather not see any warnings, either.Thanks for the help. The link you gave me helps a lot.Al