niallkennedy
commented
13 years ago I thought about how to best instruct the user on adding the namespace, preferably to the root element, html, which is not referenced in the markup snippet.
The generator could include a namespace on every generated meta element to ensure inclusion. I could group all of the meta elements as children of another element with the namespace declaration but I am unaware of a valid element (and parsing) of elements that are both a child of head and can be a parent of meta.
If a namespace declaration is used for "og" mappings, might it also make sense to include a base xmlns declaration on these elements where property is a valid attribute of meta? Some publishers may worry about validation errors thrown by HTML validators such as http://validator.w3.org/ .
tobyink
http://opengraphprotocol.us/ does not generate xmlns:og="http://ogp.me/ns#" attribute.