Re: SIunits and quantity library concerns

From: Jonathan H Lundquist (jhl_at_[hidden])
Date: 2001-10-04 15:30:12

> (5)  This is precisely what I'd like to understand better, and not only
> from "the programming perspective"!  I think that "apples" qualifies
> neither as a quantity nor as a unit, but I'm willing to be convinced to
> the contrary.  For the moment, let me apply the term "qualifier" to
> "apples" and such while I struggle to identify some of my concerns.

I've just been lurking about, and don't claim to understand all of the SI
and quantity issues, and am sure to use nomenclature which may further
confuse the issue, but all this talk about apples and oranges and such
compels me to chime in with my own problem domain.

In our software (accounting systems for packing houses) apples and oranges
would be non-fungible non-dependent attributes.  The meaning of apple
doesn't
depend on anything else, and apples and oranges don't mix.  We call these
commodities.

There are also non-fungible dependent attributes.  If a grade (measure of
quality) is named "choice", choice has a different meaning when applied to
apples as when applied to oranges.  It is dependent on the commodity.

Then there are fungible dependent attributes.  For example label, which is
just a marketing name.  Choice apples of label 'X' can be converted to
choice 
apples of label 'Y', this may require repackaging, but quantities for both
labels can be totaled when measuring the number of choice apples available.
Non-fungible quantities can not be reasonably totaled.

There are also fungible non-dependent attributes, for example production
year.
Production year 2001 (basically year harvested) means the same thing whether
applied to apples or oranges, and fruit from multiple production years can
be
totaled.

I don't *think* either the 'units' or 'quantities' discussions so far have
been
addressing any of the above.  Despite the use of commodity names in the
discussion, I think the 'quantities' folk are talking about another problem
we
deal with, which is units of measure.

Quantities can be measured in bins, cartons, bags, etc., all of which are
user-
defined units of measure.  The only way to total them is by conversion to
some
common unit of measure, which the industry calls 'carton-equivalents'.  The
conversion factors are subject to change from time to time.

Finally, some product is measured in pounds or gallons, from what I
understand
so far these are the only units we use that the 'SI' solution would help
with.

Just thought I'd try to throw in a little real-world discussion.  I think
there
are more dimensions to my particular problem than have been discussed so
far.