The most noteworthy feature of Balsa is its compatibility with SMILES. Contemporary SMILES implementations will be able to read and write Balsa strings -at least to a point. Incompatibilities will arise from three main sources: (1) those features of SMILES that Balsa has deliberately omitted; (2) those aspects of the SMILES language that are incompletely-specified, ambiguous, or self-contradictory; and (3) those features of SMILES that were deliberately disregarded by implementations.