Product Advertising API
Developer Guide (API Version 2013-08-01)

Purchase Items in a Remote Shopping Cart

When customers finish shopping and are ready to purchase items in their shopping cart, they choose a button, for example, Proceed to Checkout. This button must submit the value of the PurchaseURL. When customers click this button, the items in the Active area are moved from the shopping cart to the Order Pipeline.

This section explains how to submit the contents of a remote shopping cart for purchase.