Yahoo has unveiled a Common Tag format that makes Web content more discoverable. Vanessa Fox explains that Yahoo calls it a "new semantic tagging format" base on a RDFa vocabulary. The Common Tag
About page also suggests it fits into standards all major search engines will support.
Fox questions why anyone would want to use the Common Tag format. She writes that none of the
major search engines use semantic markup in Web search. Google is using existing standards (microformats and RDFa) to display enhanced listings. Both Google and Yahoo have told Fox they could use
metadata in Web search in the future, if it proves useful and can safeguard against spamming. So far, she admits, this hasn't happened. Fox adds that Zemanta, one founding company for Common Tag
provides plug-ins for blogging platforms to insert Common Tagging, and Wordpress strips out RDFa by default.
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