From SSKE

A system is a configuration of resources, including at least one operant resource, in which the properties and behavior of the configuration is more than the
properties and behavior of the individual resources.

A service system can be defined as an open system capable of improving the state of another system through sharing or applying its resources (i.e., the other system determines and agrees that the interaction has value), and apable of improving its own state by acquiring external resources (i.e., the system
itself sees value in its interaction with other systems).

Service systems are dynamic configurations of resources, both operant resources that perform actions on other resources and operand resources that are operated on. In this context, economic exchange depends on voluntary, reciprocal value creation between service systems (each system must willingly interact, and both systems must be improved).