The sequential Context Tree Weighting procedure [6] achieves the asymptotically optimal redundancy behavior of k/2 · (log n)/n, where k is the number of free parameters of the source and n is the sequence length. For FSMX sources with an alphabet A, this number, k, is (|A| − 1) · |Ka|. However, especially the FSMX sources often use only a few possible letters in every state. It would be nice if...