Triform approach to peak definition. Key aspects of the Triform algorithm. Part a) shows the definition of the three alternative peak-shape hypotheses Forms 1, 2, and 3 using very simplified peaks. Part b) shows this on a more realistic peak shape, using the min.z cut-off on the z1, z2, and z3 test statistics to define the start and end of the regions R of each peak-like form. Part c) shows how strand lag for a peak pair on the forward (red) and reverse (pink) strand is estimated, using the δ parameter to define an extended region. Triform uses cross-correlation on this region to estimate the optimal lag, and compares this with the minimum inter-strand lag min.lag.