In theory, each state could maintain separate sequence models. For example, the "Internal First Exon of IR" state could model codon usage separately from the "Internal Last Exon of IR" state. In practice, this results in far too many parameters to estimate given training data sizes. Instead the states are tied to 10 candidate sequence models returned by SelectModel. The models are listed with the analogous Markov models commonly used in single isoform ab initio gene finders.