The official spec had lots of maximum allowed tolerances and how to test for them. E.g. the true airspeed had to be +/- 4 knots from 150 to 300 knots and +/- 1%

The official spec had lots of maximum allowed tolerances and how to test for them. E.g. the true airspeed had to be +/- 4 knots from 150 to 300 knots and +/- 1% and less than 7 knots above that. Mach number had to be +/- 1% but no greater than 0.02 or less than 0.006 of the real Mach number.