Since you talk about objects with properties, I assume you are thinking about serializing an object graph to XML. I agree the element/attribute distinction and

Since you talk about objects with properties, I assume you are thinking about serializing an object graph to XML. I agree the element/attribute distinction and mixed content is not very useful in this context. JSON or similar is fine for such data. Structured text with metadata is something like this: <b>Hello, <a href="foo.org">world</a>!</b> The element/attribute distinction and mixed content is useful here. Btw. CData-blocks are purely an escape mechanism on the syntactic level. It should be completely transparent on the application level (e.g. like backslash escapes in a JSON string).