The words 'legal unit of measurement' are very carefully defined in the Australian 'National Measurement Regulations 1999' subtitled 'Statutory Rules 1999 NO. 110'
Of the units listed in these regulations there are:
7 SI base units of measurement
- The standard SI set
17 SI derived units of measurement
- The four that are missing on comparison with the SI pamphlet are: radian, steradian, degree Celsius, and sievert. I have no idea why these 4 were left out.
19 Non-SI units of measurement used with SI units of measurement
- The first 5 are: decibel, hectare, electron-volt, stokes, and nautical mile.
8 Additional legal units of measurement
- These are inch, foot, troy ounce, horsepower, millibar, millimetre of mercury, foot per minute, and kilocalorie. These 8 are very carefully circumscribed with a special section called 'Purposes for which additional legal units of measurement may be used' and these are essentially legacy issues such as 'millibar -- air pressure in the aviation industry' or 'millimetre of mercury -- blood pressure'.
- As time goes by this list is getting less and less; there were 43 of these in 1993 and only 8 in 1999.
Very interesting! Particularly the "nautical mile."
Can you list any of the original 43 that have been dropped?
However (and probably beyond the scope of this forum), I still wonder what an Australian court would do with a contract between and Australian firm and one from another country which used non-approved units of measurement.
Jim
