 Each type has the group name, followed by an optional positive integer.The "0" mass number denotes the usual isotope, so codice_15 matches codice_16 and codice_17 and codice_18 matches every other isotope.SLN uses largely the same bonding notation as SMILES, with codice_9, codice_20, codice_21, and codice_22 for single, double, triple, and aromatic bonds.