A: Colour scheme coded peak-list lengths in dependence of the sample support position. Blue dots – interior vertex, Green dots – end vertex, white arrows – connecting edges of the MST. The red hair-cross indicates the peak-list of origin s. B: Colour scheme coded slope coefficient of the mass- dependent calibration function in relation to sample support position. C1, C2: Strip chart of the data set for a mass range of 2210 – 2212Da (top) and 842 – 843Da (bottom), including the tryptic autolysis peaks 842.508 and 2211.100Da. Black hair-crosses – masses of peaks before calibration, red circles – masses after calibration. Vertical blue line – the exact position of trypsin autolysis masses 842.508 and 2211.100Da.