There are two sets of APIS - Inbound and Outbound.
The Inbound service gives merchants the ability to create and send shipments to an Amazon fulfillment center from your vendors.The Outbound service gives merchants the ability to ship products from Amazon FCs to their customers. This service revolves around the concept of a fulfillment order. The order contains a destination address, a shipping speed, and a list of item/quantity pairs to be shipped. The createFulfillmentOrder function is used to initiate the shipping process. They are moving forward in basically offering a wholesale version of everything the do in-house.