<complexType name="ContributorType">
<sequence>
+ <element name="username" type="string" minOccurs="0"/>
<element name="id" type="positiveInteger" minOccurs="0" />
- <!-- A contributor will contain one or perhaps both of these: -->
- <element name="username" type="string" minOccurs="0"/>
<element name="ip" type="string" minOccurs="0"/>
-
- <!-- How do I say that it can't be empty? -->
</sequence>
</complexType>