"If we are going attain any of the interoperability of Universal Synchronization, where the temporal-spatial coordinates of businesses, stores, services, work shifts, academic courses, transport schedules, entertainment and media become an integrated component of universally machine-understandable resource description, we will need to agree on effective models for the representation, storage and querying of reoccurrences. It seems reasonable that any such model should be optimized for and by the natural rhythms of everyday human planning and scheduling, as reflected in the common datetime units and their natural reoccurrences. In this paper we will try to capture the nature of these reoccurrences in a logical and mnemonic model."