According to the PMBOK (5th edition), procurement documents are "the documents utilized in bid and proposal activities, which include the buyer's invitation for Bid, Invitation for Negotiations, Request for Information, Request for Quotation, Request for Proposal, and seller's responses."
Procurement documents can help to identify stakeholders and identify risks, so they are inputs to those processes. The documents are also used to close procurements.
- RFI - Request for Information
- RFQ - Request for Quotation or Quote
- RFP - Request for Proposal