The principle CRASA's pyramidal data structure. (A) An EST sequence with four gatc pattern sites indicated in boxes. (B) A gate CR pyramid with a three-level data structure. Each bin in the matrices from Level 1 to 3 is assigned with a binary code taken from both sides of the gate pattern base by base. Partitioning of Sites 1–3 from Level 1 to 3 is shown here to illustrate the progression of binary codes and data structure in a hierarchical order.