Gives fundamental parameters aggregated over the entire structure: number of elementary units, number of terminal units, total length, volume, surface area and others. Most of these parameters are self-explanatory. The “average contraction factor” is the mean value of the ratios l/l_m, where l is the length of an elementary unit not prolonging the axis of its mother unit, and l_m the length of the mother unit. (Prolongation of an axis is assumed if both units have the same branching order.) The “average branching angle” does also refer only to non-prolonging, i.e. properly branching units.