If we use the attribute "noNamespaceSchemaLocation", we say that the schema is for element from null namespace.

See, how easily this can be accomplished using Relax NG. The pattern <name ns="">root</name> says, that the root element must be named "root" and that it must be from null namespace.

If we use the attribute "schemaLocation", we say that the schema is for element from some particular namespace. In schema, you need to use the "targetNamespace" attribute, which defines the namespace, from which the element must be.

See, how easily this can be accomplished using Relax NG. The pattern <name ns="http://foo">root</name> says, that the root element must be named "root" and that it must be from the namespace "http://foo".

When the namespace of the root element does not match the targetNamespace, it's an error (well, I think). I would compare this to having no "matching" rules in XSLT. See ( 3.3.4 Element Declaration Validation Rules Validation Rule: Element Locally Valid (Element): no. 1 ). We can't say what's wrong - whether the schema or the document.