RE: description for REA diagram

[Todd Boyle <tboyle@rosehill.net>]

Bob Haugen said,
>
>* Notify of Shipment results in a Shipment (an Economic Event)
>  which should fulfill one or more of the Purchase Order Line Items.
>
>* Process Payment results in a Payment (an Economic Event)
>  which pays for the Shipment (the REA "duality" relationship).

Questions:  

Under what circumstances does Shipment (an Economic Event)
result in the creation of an account receivable or claim, 
(an Economic Resource) as its duality relation?

If this example business process does not create an account
receivable, then, what business process DOES create one?  And,
how can the student decide between cases that do/don't create
a receivable?

Thank you
TOdd