<?xml version="1.0" encoding="UTF-8"?>
<xs:schema targetNamespace="http://nvoss.org/VOResource"
           xmlns:xs="http://www.w3.org/2001/XMLSchema"
           elementFormDefault="qualified">

   <xs:element name="resource">
      <xs:complexType>
         <xs:sequence>

            <xs:element name="title" type="xs:string" />

            <xs:element name="referenceURL" type="xs:anyURI" minOccurs="0"/>

            <xs:element name="type" minOccurs="0" maxOccurs="unbounded">
               <xs:simpleType>
                  <xs:restriction base="xs:string">
                     <xs:enumeration value="Archive" />
                     <xs:enumeration value="Catalog" />
                     <xs:enumeration value="Organisation" />
                  </xs:restriction>
               </xs:simpleType>
            </xs:element>

         </xs:sequence>
         <xs:attribute name="created" type="xs:dateTime" />
      </xs:complexType>
   </xs:element>

</xs:schema>