[USMA:36029] Re: More non-SI usage

[Bill Hooper]

On 2006 Feb 13 , at 8:23 PM, Philip S Hall wrote: Presumably it is OK to write Mt or megatonne? Not really.  SI discourages the creation of alternate expressions for the same size unit. Hence, if the correct SI unit for 10^12 grams is "teragram" (symbol Tg), no other name or symbol should be used. Specifically, the use of SI prefixes with non-SI units is discouraged. There are a few exceptions that are allowed for use with SI (but not part of the coherent set of SI units). These include the litre, the hectare and the tonne. (Even with the litre, the use of SI prefixes is discouraged. Instead of millilitres, the equivalent cubic centimetres is preferred. Instead of kilolitres, the equivalent cubic metres should be used. And instead of megatonnes, the equivalent terragrams should be used.) Regards, Bill Hooper Fernandina Beach, Florida, USA ==========================    Make It Simple; Make It Metric! ==========================