In response to my comment that:
> ... there are no limitations on what lengths can be
> measured in nanometres or any of the other units which are submultiples of
> the metre.
Gene Mechtly disagrees and wrote:
> Change "or any other units which are submultiples of the meter" to "any
> other submultiples of the meter" and we can agree. A submultiple is just
> that, a "submultiple", but *not* an "unit" in its own right in SI, by
> the current BIPM Brochure.
I can't agree and I base my disagreement on the message you, Gene, yourself,
kindly forwarded from Ian Mills of the CCU on 2001-06-01:
"... we (the CCU) did decide that something needed to be done about the
names "SI units" and "Units of the SI", which up to now have been taken to
mean two different things - the former being taken to refer to the base and
coherent derived units only (i.e. no prefixes), and the latter to refer to
all units including prefixes (i.e. including the cm, mm, km, etc.). We
decided that both "SI units" and "units of the SI" should be names that
cover the whole lot ...".
The first part clearly indicates that the word "units" includes the
multiples and submultiples like miilimetre and kilometre. The second part
goes even further (and further than I was suggesting) and says that even the
phrase "SI unit" may now be applied to the prefixed units.
I don't know if this decision by the CCU has received or needs approval by
CGPM or others, but even if not, the first part of Mills's message clearly
indicates that the submultiples (and multiples) may be called "units".
Regards,
Bill Hooper
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Keep It Simple!
Make It Metric!
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