Get rid of “Bad value X-XRDS-Location for attribute http-equiv on XHTML element meta.” in XHTML5 validation

Question

I have an XHTML 5 page served with application/xhtml+xml which I want to get to validate, but the validator gives me trouble in its validation results:

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Answer 1

http://www.w3.org/TR/html-markup/meta.html says:

Changes in HTML5

Although previous versions of HTML allowed the http-equiv attribute on the meta element to have any number of possible values, the http-equiv attribute is now restricted to only the specific values described in this reference. Also, the new charset attribute is now allowed.

So, yes, it is not allowed anymore.

Answer 2

In (X)HTML5, you may only use http-equiv values that are

• defined in the HTML5 spec, or
• registered in the WHATWG wiki page "PragmaExtensions".

If you think X-XRDS-Location would be a useful value, you’d have to register it.