The three types of flow in supply chain management are make-to-stock (MTS), make-to-order (MTO), and engineer-to-order (ETO).
MTS is the most common type of flow, and is used when products are mass-produced and kept in stock until they are needed. This type of flow is often used in conjunction with just-in-time manufacturing, in which products are only made as they are needed, and there is no inventory.
MTO is used when products are made to order, rather than being kept in stock. This type of flow is often used for custom products, or for products that have a long lead time.
ETO is used when products are highly customized, and each order is different. This type of flow is often used in the construction and engineering industries.