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htmltagsw3cw3c-validation

HTML5 valid namespace tag prefixes

When validating my page, the W3-Validator gives me an error for every

<tag addthis:title="AddThis share title" />

attribute in my code. How can I make those attributes valid for HTML5, so the page validates? I need those tags so addthis uses the correct titles for my sharing links, so I can't get rid of them...

Solution

  • You can't make them valid. Not in HTML, not in XHTML. The only valid custom attributes allowed in HTML5 start "data-".

    You could make your markup valid HTML5+something or XHTML5+something, but getting a validator to check for that is a non-trivial task.