We now summarize differences among the parameters assigned to the host αCD by SMIRNOFF99Frosst, a descendant of parm99 and parm@Frosst; GAFF v1.7 (released circa March 2015 according to gaff.dat distributed with AMBER16); and GAFF v2.1 (which has not yet been published). On going from GAFF v1.7 to GAFF v2.1, the bond and angle parameters were updated to reproduce small molecule geometries obtained from high-level quantum mechanical calculations and vibrational spectra of over 600 molecules; the torsion parameters were optimized to reproduce the potential energy surfaces of torsion angles in 400 model compounds; and the Lennard-Jones coefficients were redeveloped to reproduce interaction energies and pure liquid properties, as specified in the footer of gaff2.dat provided with AmberTools18. Note that chemically analogous atoms, bonds, angles and torsions in αCD and βCD are assigned identical parameters.