This British Standard provides a schedule of tables relating to altitudes, airspeeds and Mach numbers for use in aeronautical instrument design and calibration.
The size of the tables have been restricted and the units used for the various parameters have been kept to a minimum, namely, altitude in geopotential feet, pressures in millibars and inches of mercury, airspeed in knots, and temperature in degrees Celsius.
NOTE Altitude measurements are based on the geopotential foot, and, in speed measurements where the 'knot' is involved, this is taken to mean one international nautical mile per hour.
BS 2G 199:1984 history
1984BS 2G 199:1984 Schedule for tables relating to altitudes, airspeed and Mach numbers for use in aeronautical instrument design and calibration