line 1 column 1 - Warning: missing <!DOCTYPE> declaration
line 1 column 1 - Warning: <html> proprietary attribute "xmlns:v"
line 1 column 1 - Warning: <html> proprietary attribute "xmlns:o"
line 1 column 1 - Warning: <html> proprietary attribute "xmlns:w"
Info: Document content looks like HTML5
4 warnings, 0 errors were found!

About HTML Tidy: https://github.com/htacg/tidy-html5
Bug reports and comments: https://github.com/htacg/tidy-html5/issues
Or send questions and comments to: https://lists.w3.org/Archives/Public/public-htacg/
Latest HTML specification: http://dev.w3.org/html5/spec-author-view/
Validate your HTML documents: http://validator.w3.org/nu/
Lobby your company to join the W3C: http://www.w3.org/Consortium
