DELCRI, an enantiomorph-specific figure of merit

A figure of merit DELCRI, with estimates Δ₃ for the absolute values of the triplet phase sums φ₃, is described for the selection of numerical values of symbols used in a symbolic addition procedure. From tests with a number of structures crystallizing in polar space groups this figure of merit was found to enable the selection of enantiomorph-specific phase sets.