Find below link to a very comprehensive Purchasing manual for most commonly used proccesses in SAP MM. Content of this step-by-step guide is as following;
- Purchase requisition: Create Purchase Requisition for Account Assignment, Asset, Non Valuated materials, Stock materials [ME51N], Change Purchase Requisition [ME52N], Display Purchase Requisition [ME53N], Assign source of supply to requisitions [ME56]
- Request for Quotation: Create Quotation [ME41], Maintain Quotation [ME47], Display Quotation [ME48], RFQ Comparison [ME49], Message Output RFQ [ME9A]
- Contract/APO: Create Contract with reference to PR [ME31K], Create Contract with reference to RFQ [ME31K], Change Contract [ME32K], Display Contract [ME33K]
- Purchase Order/Release Order: Create Purchase Order for Account Assignment Asset, Non Valuated materials, Stock materials, Subcontracting & Repair [ME21N], Change Purchase Order [ME22N], Display Purchase Order [ME23N]