[jbpm-users] How to define some additional attributes in ProcessDefinition

Sorry,I forget to write a title in last message. There is a sub system in my JavaEE application,this sub system manage the process definitions. There are many entities in my applicatoin, like Document,Message and so on. Each process definition must define an attribute to describe what kind of entity will be send or received in this process. In xpdl,I can write an ExtendedAttribute in the process definition like this: <ExtendedAttribute Name="entityType" Value="Message"/> So,where should I write this attribute in jpdl? Thanks.