Before revision: The offset 32.184 seconds was the 1976 estimate of the difference between Ephemeris Time (ET) and TAI, "to provide continuity with the current values and practice in the use of Ephemeris Time".IAU Commission 4 (Ephemerides), Recommendations to IAU General Assembly 1976, Notes on Recommendation 5, note 2 TAI is never revised once published and TT(TAI) has small errors relative to retrospective realizations such as TT(BIPM), on the order of 10-50 microseconds.
After revision: The offset 32.184 seconds was the 1976 estimate of the difference between Ephemeris Time (ET) and TAI, "to provide continuity with the current values and practice in the use of Ephemeris Time".IAU Commission 4 (Ephemerides), Recommendations to IAU General Assembly 1976, Notes on Recommendation 5, note 2 TAI is never revised once published and TT(TAI) has small errors relative to TT(BIPM), on the order of 10-50 microseconds.