yahoo rejected our RSS feed, saying that we need to insert <guid> elements. Ok, fine, but I was curious as to what should be put in there. I mean, is it normally displayed in the output from an aggregator? If so, then it'd be pointless putting a link to the article there, as its already in the <links> tag. So, what /can/ be put in a <guid> tag? Anything?
the best official source are the RSS 2.0 specs at http://blogs.law.harvard.edu/tech/rss or about guide from their page http://blogs.law.harvard.edu/tech/rss#ltguidgtSubelementOfLtitemgt " <guid> is an optional sub-element of <item>. guid stands for globally unique identifier. It's a string that uniquely identifies the item. When present, an aggregator may choose to use this string to determine if an item is new. " a unique identifier for example can either be an md5sum OR easier the URL of the article linked to the RSS if that URL is a link it looks like: <guid isPermaLink="true"> link to your news post</guid> </item> and if it is NO link then of course it would be <guid isPermaLink="false"> any globally unique identifier </guid> since most use software to automacally create the "guid"-string creativity certainly is possible by adding any of the unique macros a CMS template offers i could imagine that even the UNIX time in seconds added to the domain-string for an individual post would be an easy option to create to have a GLOBALLY unique identifier i have simply added the URL once more into the guid and have no problems so far