HTML5 validator failing on Facebook OpenGraph XML Namespace xmlns:og
问题 HTML 5 validator is failing on my code despite me following the Facebook documentation to the letter. There are a variety of problems but let's start with one example to start with. I'm following the Facebook "Getting Started" documentation and using th5is code: <html xmlns="http://www.w3.org/1999/xhtml" xmlns:og="http://ogp.me/ns#" xmlns:fb="http://www.facebook.com/2008/fbml"> The only difference is I precede this with <!DOCTYPE html> for HTML5. When running it through the W3C HTML5