lexType&gt;

  &lt;!-- PackageType creates a unique ID for a package / if no version specified use "latest" --&gt;
  &lt;xs:complexType name="PackageType"&gt;
    &lt;!-- vendor of the package --&gt;
    &lt;xs:attribute name="vendor"  type="xs:string" use="required" /&gt;
    &lt;!-- name of the package --&gt;
    &lt;xs:attribute name="name"    type="xs:string" use="required" /&gt;
    &lt;!-- version of the package (no range supported) --&gt;
    &lt;xs:attribute name="version" type="PackVersionType" use