Pull'ing a specific document

Hi

 

In initial conversations with partners/customers over AS4, I
have repeatedly heard the request to be able to Pull a particular document. The
unique identifier could be based on the UserMessage that has been exchanged
earlier e.g. PO # if a PO Message has been sent earlier. 

 

Is there provision in the current spec to be able to support
that ? My  understanding is that it is a generic Pull where the next available
document is sent in the response.

 

Any advice please ?

 

Thanks

Makesh