Balsa only supports two stereodescriptors, encoded with the terminals "@" and "@@." provides a recursive grammar for stereodescriptors that allows multi-symbol descriptors such as "@@@" and "@@@@" ]. ProtoSMILES also supports non-tetrahedral descriptors including "@AL1," "@AL2," "@1," and "@SP1." None of these are supported by Balsa. Nor does Balsa support the application of tetracoordinate stereodescriptors to odd cumulenes. These other forms of atomic configuration are relatively rare. Their inclusion in Balsa would add substantial cost for little gain.