The intention of Simple Extension Elements is to provide a simple class of extension that is part of the Atom model, and can therefore be preserved end-to-end by implementions via publishing clients, servers, databases, and aggregators.
We say that Simple Extension Elements are not language sensitive, but we don't say that Simple Extension constructs aren't affected by xml:base. I think that the implication is that they are not, but it is not very explicit: > [...] Simple Extension elements are not Language-Sensitive. The > element can be interpreted as a simple property (or name/value pair) > of the parent element that encloses it. [...] The character data > content of the element can be interpreted as the value of the > property. If the element is empty, then the property value can be > interpreted as an empty string. It doesn't make sense for Simple Extension Elements to be affected by xml:base, because that requires extensions specific processing to know whether the extension is intended to be a URIRef or not; avoiding extension specific processing is the reason for Simple Extension Elements existence. Can we add some clarification? -- Dave
