On Sat, 14 Dec 2002, Terry Simpson wrote: > ... > Despite the kilogram being the base unit, the names are manipulated as if the base unit were the gram. Part of the true SI sequence for mass is: ...
To escape this anomaly, in documents covering a wide range of values, I prefer to use the "E" format: e.g. 3.21 E-6 kg, 3.21 E-3 kg, 3.21 kg, 3.21 E3 kg (or 3.21 tons), 3.21 E6 kg, etc. If the range is within one prefix and has enjoyed wide usage historically, e.g. 1 mg to 100 mg for medications, I would not object to multiples of the gram. However, on the high side, Mg and Gg have never been used widely, so I recommend use of the ton = 1 000 kg, or the "E" notation. > The tonne is a table 6 unit and is therefore non-SI but 'accepted for > use'. So it is acceptable to have: > > �t microtonne > mt millitonne These two are technically correct, but E-6 x E3 kg = E-3 kg (or 1 g) are preferable; and E-3 x E3 kg = 1 kg is preferable. > t tonne > kt kilotonne > Mt megatonne > Gt gigatonne These four are also technically correct, have won extensive usage, and are not objectionable in my opinion. > I have seen tonne and larger multiples such as kilotonne. However, I do > not regard these as anything other than commonly used non-SI anomalies. Anomalies? Yes. Approved for use with SI units? Yes. > Are you suggesting that the normal SI prefixes should not apply for > mass? No, but applied according to the preferences I cited above. Gene.
