Standardisation of CxSMILES was based on ChemAxon Standardizer and included the following actions: removal of R-group definitions; conversion of pseudo and alias atoms to existing chemical elements; expansion of S-groups; conversion of hydrogen atom isotope representation from D/T to 2H/3H atom symbols; conversion of isotopes to the particular chemical element; conversion of single bond between metal atom and multicentre to coordinate type; conversion of explicit hydrogens to implicit ones for bridgeheads, S-groups and hydrogens connected to elements with a valence error; removal of atom values, attached data and stereo search markers; rearrangement of stereo wedge bonds according to IUPAC recommendations; conversion to a standard representation for aromatic and tertiary N-oxides, azides, diazo, diazonium, iminium groups, isocyanates, nitrilium and nitro, nitroso, nitrone nitronate, phosphate, phosphonium ylide groups, selenates, silicates, sulfines, sulfons, sulfonium and sulfoxonium ylides, sulfoxides; conversion of charge separation between sulphur, nitrogen, phosphorus and oxygen to a double bond of an oxide; conversion of an ionic bond between magnesium and halide in Grignard reagents and between zinc and halides in organo-zinc reagents to a covalent bond; mesomerisation; tautomerisation; neutralisation and aromatisation.