How does an OrderResponse show order acceptance/rejection?

Looking at how all the documents of UBL 1.0 might
be used together in a business process, I come across
a problem: if the Order has its 
AcknowledgementResponseCode set to "OrderResponse" 
by the Buyer, how would the OrderResponse indicate
whether the Order has been accepted or rejected?
(OrderResponseSimple has AcceptedIndicator)

Thanks for any light anyone can shed on this.

All the best

Stephen Green