The structure of the discrete state-space model (DSM) used to model 3'-processing control sequences for yeast. All state-to-state transitions not explicitly labeled have a probability of 1.0. The hexagonal elements are background elements that can take on any length in the given range with equal probability. The functional elements e1-e4 are hexamers, with individual nucleotide frequencies determined through analysis with the Gibbs Sampler. Probabilities p1-p4 were optimized empirically in analysis of known processing sites. The position of the cleavage and polyadenylation is the center of the c element. Nucleotide probabilities for the c element were obtained from the 1,352 training sequences.