HTML5 Pass-Through Element Causes Eclipse Warning 'Unknown Tag'

My JSF template.xhtml file looks something like: <main> as a tag registered in the default XML namespace as identified by http://www.w3.org/1999/xhtml. Eclipse holds an internal list of registered tags. If upgrading to latest Eclipse (SR) version doesn't solve the problem, then your best bet is to report this as an issue to Eclipse guys. In the meanwhile, just choose the quick fix option "Ignore 'main' element in HTML5 validation".

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Unrelated to the concrete problem, that XML prolog doesn't belong there. Get rid of it. Further I also wonder the necessity of the "header", "nav", "main" and "footer" being whole JSF components. I'm not really seeing any useful real world appliances with this. You'd most likely as good just keep them plain HTML. This saves you from unnecessary overhead.

See also:

• XML prolog / instruction not removed from XHTML output
• JavaServer Faces 2.2 and HTML5 support, why is XHTML still being used