Figure 1  Loops with cuts have to be scored differently. Top row: hairpins and interior loops containing the cut between n1 (black ball) and n1 + 1 (white ball). Below: multi loops containing the cut. Neither M1 nor M components must start at n1 + 1 or stop at n1. Note that the construction of ZM out of ZM and ZM1 ensures that the cut is not inside the loop part of ZM either.