When you create a service activity in your network, you can enter a service specification, an overall limit, and a vendor. The service specification defines the scope and details of the service to be performed. The overall limit sets a maximum value for all unplanned services that can be entered during service entry. The vendor specifies the external service provider who will perform the service. Reference: https://help.sap.com/doc/0f069b2e08b748f1b480d4c8b46c3c49/100/en-US/6a7a9f0a6e421014e10000000a174cb4.html