2.1.1.1.2.2 req

The req (request) element is a child element of reqs. It describes a client request of the server. The attribute name is key and represents a message-wide unique key associated with the req element.

 <xs:element nm="req" minOccurs="1" maxOccurs="unbounded">
  <xs:complexType>
   <xs:attribute nm="key" type="xs:string" use="required"/>
  </xs:complexType>
 </xs:element>