When planning maintenance work that is to be carried out by an external company, you have to consider the following aspects:

If you assign a control key with indicator “Service” for an external service, you have to enter the actual values via the service entry sheet. This is because the service entry sheet is used to record the services performed by the external company and to verify the invoice. The service entry sheet is linked to the purchase order and the maintenance order operation.

For the maintenance order type, you have to assign the Enhanced Procurement Mode. This is because the Enhanced Procurement Mode enables you to use lean services and enhanced limits for external services. Lean services are intended for the procurement of small or highly specialized services that are carried out by external suppliers as part of an internal or external operation. They can be maintained in the material master as service products. Enhanced limits allow you to define a maximum amount for the external service without specifying the service specifications in advance.

If you assign a control key for an external order operation, the actual values must always be entered as a goods receipt in the system. This is not true, because the goods receipt is only required for external materials, not for external services. For external services, the service entry sheet is used instead.

In the control key assigned to the order operation, the “Service” indicator must always be activated. This is not true, because the “Service” indicator is only required for external services, not for external operations. For external operations, the “External Processing” indicator must be activated instead. References: External Services Management (MM-SRV) | SAP Help Portal, Highlights for Asset Management in SAP S/4HANA 2021 | SAP Blogs.