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I have a HTML5 based page, and I inculded the OpenGraph tags according to it's documentation. Also I checked with Facebook Debug, and it can parse the metadata. But when I use W3C Validator, it reports the OG tags as error:

Attribute content not allowed on element meta at this point. <meta property="fb:admins" content="...." />

Attribute content not allowed on element meta at this point. <meta property="og:url" content="http://www....">

They are all in the <head>. I would need my page be "valid" HTML5 and OG tags, as well. Could you help me giving a hint how can it be achieved?

UPDATE: The name version also invalid: <meta name='fb:admins' content=''>

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Ain't facebook using RDFa on opengraph etc tags? With html5 it's under development dev.w3.org/html5/rdfa/rdfa-module.html – user14712 Apr 16 '12 at 7:40

Ultimately this type of metadata is never going to be part of the W3C spec and is therfore never going to be seen as valid by any validation engine.

I've used name instead of property before. Facebook's validator throws a warning but still parses the data and the page then passes a w3c validation.

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I got errors for the name version, as well: Bad value fb:admins for attribute name on element meta: Keyword fb:admins is not registered. – netmano Mar 1 '12 at 12:06
@netmano can you post a link or post a js fiddle of the code? – toomanyairmiles Mar 1 '12 at 18:52

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