One statement that describes subnetworks is that the scheduling type of a subnetwork is always copied from the superior network. A subnetwork is a network that covers only part of a project and is linked in relationships with other subnetworks in the same project. A subnetwork can be used to refine and detail your networks as planning progresses. The scheduling type is a parameter that determines how the dates of activities and networks are calculated based on their dependencies and constraints. The scheduling type of a subnetwork is always copied from the superior network when creating or changing a subnetwork. The scheduling type of a subnetwork cannot be changed independently from the superior network. Reference: https://help.sap.com/doc/0f069b2e08b748f1b480d4c8b46c3c49/100/en-US/f373bb53707db44ce10000000a174cb4.html