<grammar xmlns="http://relaxng.org/ns/structure/1.0" ns="urn:test:simple.rng">
  <start>
    <choice>
      <element name="simple-element">
        <ref name="simple-element" />
      </element>
      <element name="optional-element">
        <ref name="optional-element" />
      </element>
      <element name="simple-attribute">
        <ref name="simple-attribute" />
      </element>
      <element name="optional-attribute">
        <ref name="optional-attribute" />
      </element>
      <element name="fixed-attribute">
        <ref name="fixed-attribute" />
      </element>
      <element name="attribute-choice">
        <ref name="attribute-choice" />
      </element>
      <element name="value-choice">
        <ref name="value-choice" />
      </element>
      <element name="token-datatype">
        <ref name="token-datatype" />
      </element>
    </choice>
  </start>

  <define name="attribute-choice">
    <choice>
      <group>
        <attribute name="type">
          <value>a</value>
        </attribute>
        <element name="a"><empty /></element>
      </group>
      <group>
        <attribute name="type">
          <value>b</value>
        </attribute>
        <element name="b"><empty /></element>
      </group>
    </choice>
  </define>

  <define name="simple-element">
    <element name="b">
      <empty />
    </element>
  </define>

  <define name="optional-element">
    <element name="b">
      <optional>
        <element name="c">
          <empty />
        </element>
      </optional>
    </element>
  </define>

  <define name="simple-attribute">
    <attribute name="x" />
  </define>

  <define name="optional-attribute">
    <optional>
      <attribute name="x" />
    </optional>
  </define>

  <define name="fixed-attribute">
    <attribute name="x">
      <value>1.0</value>
    </attribute>
  </define>

  <define name="value-choice">
    <attribute name="x">
      <choice>
        <choice>
          <value>a</value>
          <value>b</value>
        </choice>
      </choice>
    </attribute>
  </define>

  <define name="token-datatype">
    <attribute name="a"><value>v</value></attribute>
    <attribute name="b"><value>v</value></attribute>
    <attribute name="c"><value>x y</value></attribute>
    <attribute name="s1"><value type="string">v</value></attribute>
    <attribute name="s2"><value type="string"> v </value></attribute>
    <attribute name="s3"><value type="string">v</value></attribute>
  </define>
</grammar>