1. A method for compressing digital data to compressed data, which comprises a stream of data words and control words, the method comprising the steps of: receiving a current word of digital data; comparing the current word of digital data to at least one previously processed word of digital data to establish if the words are identical, wherein the at least one previously processed word is selected based on a dynamic set of offset values, an offset value being associated with a number of words between two digital data words; and if an identical previously processed word of digital data is found, affixing to the compressed data a control code including an indication of the offset value.