<xsd:attribute name="header" type="xsd:string" use="required" />
<xsd:attribute name="extension-xname" type="xsd:string" use="optional" />
<xsd:attribute name="extension-name" type="xsd:string" use="optional" />
+ <xsd:attribute name="major-version" type="xsd:integer" use="optional" />
+ <xsd:attribute name="minor-version" type="xsd:integer" use="optional" />
</xsd:complexType>
</xsd:element>