and rendering. ISIS/Draw also included structure and reaction validation features and could calculate elementary properties such as formula and molecular weight. It had an "AutoNom" add-in that allowed the creation of IUPAC names for valid structures and could use a special "pseudoatom" to generate amino-acid sequences for proteins. One important feature of the MACCS system and ISIS/Draw was that it had comprehensive facilities, using hatched and wedged bonds, to represent relative or absolute stereochemistry and chirality and to recognise cis–trans isomerism in double bonds. In this respect it was superior to Wiswesser line notation which had hitherto been used to create searchable databases. Likewise, while SMILES notation can handle stereochemistry in some implementations it is more difficult for non-specialists to encode their structures in that way than by drawing them. Current implementation The current (2020) implementation of the software is called BIOVIA Draw and has several new features such as support for reading and writing International Chemical Identifiers (InChi) and converting IUPAC names into structure drawings. It is freely available for academic and non-commercial use. See also MDL Chime Molecule editor References Further reading Chemistry software