3.6.4.12.3.2 RegisterCoreEventSinkResponseBody

 <xsd:complexType name="RegisterCoreEventSinkResponseBody">
   <xsd:sequence>
     <xsd:element minOccurs="0" maxOccurs="1" name="pullCookie" type="xsd:unsignedLong"/>
   </xsd:sequence>
 </xsd:complexType>

pullCookie: Contains a unique identifier to be used to unregister at a later time.