Purchasing defines the procurement of either a material and/or services. It can be either external or internal.
w.r.t materials, it can be for stock purposes or consumption purposes.
The purchasing document types can be of Internal (for PR) or external (RFQ, PO Quotation, Contract and schedule agreement)
Item Category: specifies how the procurement of material/services to be controlled.
Account Assignment category: If the purchase order is created for stock purpose, we leave this field blank. If for consumption purpose we give any acct assign cat.
Request for Quotation:
ME49 gives price comparison
goods receipt: Maintain received goods in Inventory. The movement type controls the movement of goods in and around the storage location/plant
Contract: Contains pre-defined terms and conditions (ME31K)
Scheduling Agreement: contains Delivery date and time.
Delivery date and time is required in schedule agreement and no purchasing order and no release order
There can be scheduling agreement with another plant in same company but it is not possible with contracts.