Fig. 3

Optional sub-layer composition: An optional sub-layer is directly located after the main sub-layer. Such a code is composed by the symbol ‘/’ followed by a letter and indicates the modification (/c for charge, /i for isotope and /s for stereochemistry). Each block qualifying an atom or a bond is composed of four characters. The first two characters are a number (2 characters) indicating the index (decimal system) of the entity (atom or bond) in the current layer which has to be modified. The next 2 characters are encoding the change to apply to reactants (first character) and products (second character) (for isotope and charge see Additional file 1: Table S3; for atom stereochemistry see Additional file 1: Table S4; and for bond stereochemistry, see Additional file 1: Table S5)