Get the attachments files of negotiation in Sourcing Module

Hello,

I’m  working in Sourcing, with Negotiation. I want to make a query to get the attachment file of the supplier.
For example, We have a negotiation number = 706, and this negotiation has four rows in Deliverable section (Contract Terms). One supplier put two files in deliverable section ( attachments files).
I can see this tables:
okc_deliverables (has the deliverable names to negotiation number 706)
fnd_documents_tl (has the attachments files)
fnd_attached_documents (has de ID attachments files)

But I don't know how is the relationship into this tables, I have the negotiation number and supplier ID.

Could you give me a script to get the files attachments? Or Could you tell me how is the relationship.