Let's start with our first document. It must have only "root" element and this element can contain text only. The element is from null namespace.

Relax NG does not interfere to the structure of the validated document.

Now, let's have the same document as in previous example, but the "root" element must be from some concrete namespace, let's say "http://foo".

We allow the "root" element to be from several namespaces, let's say: "http://foo", "http://bar", or "http://baz". That's not possible in XML Schema.

The treating of namespaces in Relax NG is smooth, consistent, natural, and easy.