Confirmation of External Services or External Material 
Purpose
If you schedule external material or external services in service and maintenance orders, you use external procurement processing for their completion confirmation.

There are companies, which also want to perform capacity planning for employees from external companies. In such a case, it is possible to create service or maintenance orders, in which you plan the required external capacity, in addition to the external procurement processing described here, which is processed by Purchasing. These orders are then confirmed regularly by the employees from the external company to break down the planned capacity. For these completion confirmations, the employees from the external companies can use the
For this type of processing, a control key, which allows capacity requirements to be determined, must be assigned to the external operations.
See also:
Control KeyProcess Flow

If changes, with reference to the materials/services ordered (for example, different dates or quantities), occur in the order owing to the planning and executing of maintenance work, the system automatically changes the quantities if you are using SAP Business Workflow in your system and have made the necessary settings for this.
For more information, see
Change of a Purchase Requisition.
Especially for External Services:
The service is valuated with the purchase order price and entered in the accounts of Financial Accounting. The order used to order the service is charged with this value.
After a goods receipt for an operation, which is to be executed by an external company, this operation automatically receives the status External operation partially delivered. The operation only receives the status External operation delivered when the final delivery indicator is set for the goods receipt.
In the order, on the external processing screen for the operation, you can see whether a goods receipt has been posted for the purchase order. You can see the goods receipt quantity posted in the field GR qty.
For more information about external services, see
Order Processing (External Assignment).See also:
Manual Creation of Purchase Requisitions
Change of a Purchase Requisition