Thanks for the responses folks.
So if the SuD receives or sends data to/from an external system, e.g. inventory information via a web service call to an inventory system, in the integration tier I could represent this by Inventory DAO or Inventory Web Service. If I mention Web Service(rather than DAO) should it read Inventory Web Service Client or Inventory Web Service.
Similarily, if I interact with an external system(SYSTEM_A) via messaging, I could represent this as SYSTEM_A DAO or SYSTEM_A JMS Client(or SYSTEM_A JMS)
Thanks
Joe