Active databases are an important topic of current database research. However, the semantics of the underlying mechanism, event-condition-action rules (or ECA rules for short), is unclear so far. In order to define a clear semantics for sets of active rules, we first derive the requirements such a semantics must fulfill. Since currently no semantics fulfills these requirements, we continue with the definition of the PARK semantics adhering to all requirements. The PARK semantics is a smooth integration of inflationary fixpoint semantics [7] with conflict resolution. Through this approach, the PARK semantics is powerful enough to deal with recursive active rules. Furthermore, the actual conflict resolution strategy is a parameter of the PARK semantics. This guarantees a wide range of applicability.