Dear Ingvar, (01)
When you introduce the use of the term "nominal", it needs to be defined.
I'm not aware of its usage in the standard, nor do I understand a need for it. (02)
I would not agree that "many units are unambiguously tied only to one
The number of derived quantities is unbounded as is the number of dimensionless
derived quantities. I only need multiply one dimensionless derived quantity
each derived quantity having nontrivial dimension and presumably I will have
at least two kinds of quantity for each coherent derived unit. (04)
Unless you only are referring to things like joule, which is not a coherent
derived unit. (05)
Perhaps the use of the bare term "unit" is sloppy.
Let me suggest SICDU, SIBU, SIDU, and NSIU as abbreviations for SI coherent
derived unit, SI base unit, SI derived unit (not coherent), and non-SI unit. (06)
I believe that the principal units of our concern should be coherent derived
units, of which SIBU is a subset. (07)
> Dear Joe,
> Jump to the end of the mail; there is my responsse.
> I am as aware of the contents of VIM as of the SI brochure, and your
> "n.b." makes exactly my point. What you might call "newton-meter as a unit
> alone", I prefer to call "nominal newton-meter". However, note that only
> some units can be called nominal units and tied to more than one
> kind-of-quantity; many units are unambiguously tied only to one
Joseph B. Collins, Ph.D.
Code 5583, Adv. Info. Tech.
Naval Research Laboratory
Washington, DC 20375
(202) 767-1122 (fax)
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