We discuss representations of prefix codes and the corresponding storage space and decoding time requirements. We assume that a dictionary of words to be encoded has been defined and that a prefix code appropriate to the dictionary has been constructed. The encoding operation becomes simple given these assumptions and given an appropriate parsing strategy, therefore we concentrate on decoding. The application which led us to this work constrains the use of internal memory during the decode operation. As a result, we seek a method of decoding which has a small memory requirement. Introduction Data compression is an important and much-studied problem. Compressing data to be stored or transmitted can result in significant improvements in the use of computing resources. The degree of improvement that can be achieved depends not only on the selection of a data compression method, but also on the characteristics of the particular application. That is, no single data compression algorithm wi...