The order in which words are configured is not enforced, but it is important when setting up relationships between words. See "Specifying CHANNELS" of Chapter 3, Specifying Labels and Handling Guidelines for Printer Output for examples of how the order affects how words must be encoded. See also the DIA Label Encodings Format manual referenced in the Preface.
By convention, the WORDS in the SENSITIVITY LABELS section are arranged in increasing order of importance.