Source
The SOURCE Level Two process types: source stoked product (S1), source make-to-order product (S2), and source engineer-to-order product (S3): attempt to characterize how a company purchases raw materials and finished goods.
S1, a make-to-stock environment, is generally triggered by a forecast requirement from PLAN, MAKE, or DELIVER and the supplier has the item available in a finished-goods inventory before the purchase order.
S2, a make-to-order environment, is usually triggered by a specific customer-order requirement from MAKE or DELIVER, and the supplier must convert raw materials or semi-fineshed goods in response to a purchase order.
S3, an engineer-to-order environment, is most often triggered by a specific customer order and design specifications from MAKE or DELIVER. A qualified supplier must be identified before purchase order is assued; the purchase order quality is dependent on specific customer order quantities and is often executed only once