B - Total Process Coordination
Where multiple companies may be involved, processes must be coordinated.
Typically, a retailer buys goods from vendors to sell to its customers. It may buy direct from manufacturers, or there may be one or more intermediaries (wholesalers) in-between. The retailer must coordinate with these vendors when items are on backorder. It must also coordinate with them to obtain updated information about product availability, price changes, item changes, and other things that affect they physical merchandise.
When a retailer goes online, they use third-party shipping services to deliver the goods, and must coordinate with them to make order status information available to customers (to assign tracking numbers to packages, at the least).
Many retailers will also use third-party logistics services to warehouse inventory and pick orders for mail-delivery (rather than placing the additional load on their own logistics services). They will need to coordinate to provide order status information to customers.
In some cases, this may mean getting different back-end systems to share information on a regular basis - preferably, in real-time - to support customers.
As stated earlier, the customer doesn't know who is handling the order, and doesn't care which of several companies may be at fault. To them, they are doing business with one vendor, and it falls to the vendor to manage other firms they use to support the customer.