="optional" /&gt;
  &lt;/xs:complexType&gt;

  &lt;!-- Package section type --&gt;
  &lt;xs:complexType name="PackagesType"&gt;
    &lt;xs:sequence maxOccurs="unbounded"&gt;
      &lt;xs:element name="package" type="PackageType" /&gt;
    &lt;/xs:sequence&gt;
  &lt;/xs:complexType&gt;

  &lt;xs:complexType name="LayerType"&gt;
    &lt;xs:all&gt;
      &lt;!-- layer description --&gt;
      &lt;xs:element name="description" type="xs:string" minOccurs="0" /&gt;
      &lt;!-- layer intentionally does not have 