Dispatch Document -Warehouse element

Currently we are building a dispatch document for a third party warehouse. Its clients send an instruction to pick and send items to their customer(s). Each Dispatch instruction will be to pick items from one warehouse. If stock is required from another warehouse a separate dispach will be used. I'm not sure where this should be highligted in the dispatch document. I probably dont want it at the item level.

Any suggestions would be helpful

Thanks 

XML.org Focus Areas: BPEL | DITA | ebXML | IDtrust | OpenDocument | SAML | UBL | UDDI
OASIS sites: OASIS | Cover Pages | XML.org | AMQP | CGM Open | eGov | Emergency | IDtrust | LegalXML | Open CSA | OSLC | WS-I