Interorganizational cooperation is more and more organized by the paradigm of services. Service-oriented architectures (SOA) provide a general framework for service interaction. SOA describe three roles of services, the service provider, the service requester, and the service broker, together with the three operations publish, find, and bind. We provide a formal method based on nondeterministic automata to model services and their interaction. In this paper, we restrict ourselves to finite and acyclic automata. We suggest operating guidelines as a convenient and intuitive artifact to realize the publish operation. In our approach, the find operation reduces to a matching problem between the requester's service and the published operating guidelines. If matching services are actually bound together, our approach guarantees deadlockfree communication. In this paper, matching of deterministic as well as nondeterministic automata with operating guidelines is presented. Key words: Serv...