<xs:schema attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:xs="http://www.w3.org/2001/XMLSchema">
  <xs:element name="collection" type="collectionType"/>

  <xs:complexType name="docType">
    <xs:simpleContent>
      <xs:extension base="xs:string">
        <xs:attribute type="xs:string" name="href" use="required"/>
      </xs:extension>
    </xs:simpleContent>
  </xs:complexType>

  <xs:complexType name="collectionType">
    <xs:sequence>
      <xs:element type="docType" name="doc" maxOccurs="unbounded" minOccurs="1"/>
    </xs:sequence>
  </xs:complexType>
</xs:schema>
