In the last few years, the concept of time granularity has been defined by several researchers, and a glossary of time granularity concepts has been published. These definitions often view a time granularity as a (mostly infinite) sequence of time granules. Although this view is conceptually clean, it is extremely inefficient or even practically impossible to represent a time granularity in this manner. In this paper, we present a practical formalism for the finite representation of infinite granularities. The formalism is string-based, allows symbolic reasoning, and can be extended to multiple dimensions to accommodate, for example, space.