From W3C Wiki
I think there is a subtle problem with the section on event-handlers being pulled out of the html tags. It uses a GetElementByID example, which should only have one element per page (because it's an ID, not a Class), but then mentions the advantages of using the recommended procedure because it will let the programmer avoid having to update lots of elements on the page. I would suggest either using GetElementByClass as the example instead.
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