Q: ebXML-BP MetaModel v1.0 - Business Service Interface Package

The following questions are in reference to the ebXML-BP MetaModel v1.0
Business Service Interface package modeling.

What is the purpose of the To and From relationships between Partner Role
and Information Flow? Note that Business Signal has a direction attribute on
it.  What advantage do we gain by modeling that Information Flow is To/From
a Partner Role instead of a BusinessServiceInterface?  

Please explain the "exposes" relationship between BusinessServiceInterface
and Partner Role.  What direction does the relationship go in?

Please explain the "supports" relationship between BusinessServiceInterface
and Business Signal.  Is it directional?  Is it correct to say that a
BusinessServiceInterface supports and Business Signal or vise versa?

Does the Business Signal define the Information Flow or vise versa?  Does
define mean specify?  How are Business Signal and Information Flow usefully
different?

Thank you in advance,
Brian Hayes
XML Cross Product Architect
Document Engineering. Commerce One. +1 (925) 520-4498