Thanks.
My question in my previous post was premature. I was under the impression that the BIPM doesn't have any spelling prefferences but only deals with unit symbols. If they are going to go tot he trouble of creating a term like metric ton, why not just use megagram? I also don't see what the big problem is over the word tonne. It is only used in spelling and contains only two extra letters compared to the longer word metric ton. Tolerating some units for use along with SI is not in itself modifiying SI. Wouldn't you say that still using English units in the US is tolerating obsolete units alongside SI units? I think the binary prefixes should be made a law. The metric prefixes used as binary prefixes makes matters very confusing. I'm still not sure exactly what my hard drive capacity is. Jerry ________________________________ From: John M. Steele <[email protected]> To: [email protected] Sent: Saturday, February 7, 2009 8:32:12 AM Subject: US "interpretation" of metric All are minor points and are fully explained in NIST SP330 as margin notes (they are all allowable variation mentioned in the BIPM SI Brochure): 1) US spelling: meter, liter, deka- vs. metre, litre, deca- (note that deca- and deci- differ by only one character) 2) Decimal separator is a point, not a comma. (Most English speaking nations do this) 3) "Metric ton" is preferred to "tonne" 4) The upper case symbol "L" is preferred to "l" for liter. (Several nations agree) In addition, the US interpretion "tolerates" use of some obsolete units for ionizing radiation alongside SI units, while stating the SI units are preferred; these units are embedded in US laws.. The US version more strongly advocates IEC prefixes for binary powers of 2^10 (kibi). Both SP330 and SI Brochure state power of ten prefixes 10^3 (kilo) may NOT be used to represent close binary powers. There are NO differences in the sizes of units, practical realizations of standards, or differences in symbol (except L, where two are permitted). As both documents are free downloads, you should read them.
