how do I make an element a child of itself in XML Schema?

Question

I'd like the ability to have an arbitrary level of nesting children of the same parent element, e.g.:

<path expr="/">
  <path expr="usr">
    <path expr="bin">
      <path expr="X11" />
    </path>
  </path>
  <path expr="var" />
</path>

I'm writing the XML Schema file, and I'm at a loss as to how to represent this parent/child relationship in the schema: here's what I have, but it's not a valid schema definition:

          <xs:element name="path">
            <xs:complexType>
              <xs:sequence>
                <xs:element ref="path" minOccurs="0" />
              </xs:sequence>
              <xs:attribute name="expr" type="xs:string" use="required" />
            </xs:complexType>
          </xs:element>

Update: Thanks for the response. I tried that, and I'm getting the following error: The 'w3.org/2001/XMLSchema:complexType' element is not supported in this context. I should mention that the path hierarchy as I've described is itself a child of an element called application, so the entire structure resembles this:

<application name="test">
  <path expr="/">
    <path expr="usr">
      <path expr="bin">
        <path expr="X11" />
      </path>
    </path>
    <path expr="var" />
  </path>
</application>

Answer 1

Personally I prefer RelaxNG over XML Schema. May be worth your time to try it out.