Hajo, (01)
you wrote:
> Dear Ed,
>
> I have to admit, it is confusing. First of all, I do not think that a unit of
>measure is a quantity. I know that unit of measures are ultimately defined in
>terms of quantities, but, to my understanding or perception, that is not the
>same as that a unit of measure would be a quantity.
>
I misspoke. In David's model, a 'measurement unit' is a kind of
'quantity magnitude'. A 'quantity magnitude' is an equivalence class of
particular quantities which would all compare as "equal" (assuming some
notion of uncertainty). So the length of a given table is a particular
quantity, and "1.5metres" is a name for the equivalence class (the
magnitude) to which it belongs. And "metre" is itself defined as the
magnitude (the equivalence class) of a particular reference quantity,
which is some wavelength. "1.5 metres" is a 'quantity value', which is
an expression of a magnitude as a ratio to a 'measurement unit' (at
least in this case), but the same magnitude can have other
names/expressions using other units. (02)
(This terminology assumes that 'quantity' is a synonym for 'particular
quantity'.) (03)
> Second, I would like to learn more about the term "kind" as it is used in
>VIM. Probably, then I will get to understand the use of the term better.
>Again, if someone could send me a link, I would be very grateful.
>
The VIM is a publication of the BIPM, available at:
http://www.bipm.org/en/publications/guides/vim.html (04)
The important thing here is that VIM does not use 'kind of quantity' to
mean "classifier that 'is a kind of' quantity". It means such a
classifier with the restriction that all of the particular quantities
that satisfy it are comparable. A class of quantities that includes
both heights and weights, for example, is not a 'kind of quantity', even
though all of its instances are particular quantities. (05)
-Ed (06)
--
Edward J. Barkmeyer Email: edbark@xxxxxxxx
National Institute of Standards & Technology
Manufacturing Systems Integration Division
100 Bureau Drive, Stop 8263 Tel: +1 301-975-3528
Gaithersburg, MD 20899-8263 FAX: +1 301-975-4694 (07)
"The opinions expressed above do not reflect consensus of NIST,
and have not been reviewed by any Government authority." (08)
_________________________________________________________________
Message Archives: http://ontolog.cim3.net/forum/uom-ontology-std/
Subscribe: mailto:uom-ontology-std-join@xxxxxxxxxxxxxxxx
Config/Unsubscribe: http://ontolog.cim3.net/mailman/listinfo/uom-ontology-std/
Shared Files: http://ontolog.cim3.net/file/work/UoM/
Wiki: http://ontolog.cim3.net/cgi-bin/wiki.pl?UoM_Ontology_Standard (09)
|