PO

Using this module client can create requisitions, purchase orders, requests for quotoation and receipts quickly and effectively.
4 Types of POs
1.Standard PO
2.Planned PO
3.Blanket Purchase Agreement
4.Contract Purchase Agreement

Client/Customer will have option to enter below
Price
Quantity
Terms&conditions
Goods& services
Delivery schedule
Accounting and
Supplier shipment authorization

Clinet/Customer creats...
Standard PO, when he want vendor commitment and to specific item or service for a particular scheduled time, but long-term agreement is not appropriate.

Planned PO, when customer want long-term agreement committing to buy items or services.

Blanket PA/Release, this will be created with negotiated volume discounts and want to create blanket releases against agreement to place actual order.

Contract PA/Release, customer will do this without indicating goods or services. Later will create po on these contracts.

Global Agreements: Buyers can negotiate price & terms. Later will create po on these.

PO APIs:
1.Open Requisition Interface-->Upload requisitions
PO_REQUISITIONS_INTERFACE_ALL
PO_REQ_DIST_INTERFACE_ALL
2.Purchasing Document Interface-->Upload purchase orders, responses to RFQs
PO_HEADERS_INTERFACE
PO_LINES_INTERFACE
PO_DISTRIBUTIONS_INTERFACE
3.Receiving Open Interface-->Upload receipt information into
RCV_HEADERS_INTERFACE
RCV_TRANSACTIONS_INTERFACE

Matching:
2-way matching
invoice price <= PO price
quantitiy billed <= quantity ordered

3-way matching
invoice price <= PO price
quantity billed <= quantity ordered
quantity billed <= quantity received
4-way matchinginvoice price <= PO price
quantity billed <= quantity ordered
quantity billed <= quantity accepted

Good Links
http://www.oracleappshub.com/oracle-purchasing/po-tips-and-useful-query/