A derivative of the SMILES language that describes the transformation in a chemical reaction.
Examples: The hydrolysis of methyl formate is written "C(=O)OC>HOH>C(=O)O.OC".
Source:
PAC, 2016, 88, 239. 'Glossary of terms used in computational drug design, part II (IUPAC Recommendations 2015)' on page 257 (https://doi.org/10.1515/pac-2012-1204)