The combination of IAU1976 precession, IAU 1980 nutation, IAU 1982 GMST and IAU 1994 equation of the equinoxes give errors in the final result of up to about 0".05. At present, and with free core nutation neglected, the IAU 2000A based models are at least two orders of magnitude better to 200 microarcseconds for the periodic terms and from 0.3"/c to 0.003"/c for secular terms. Even using the truncated nutation series, IAU 2000B, the improvement is at least a factor of 30.
