Burkett, William [USA] wrote:
>> Please, Chris, Matthew, or David, expalain what the ISO distinction
>> between direct and indirect properties amounts to.
>>
>
> I think "indirect property" is a poor name for the thing called "maximum
>allowable operating temperature" (if I may go back to that original example.)
>That thing is, IMO, a property of an abstract "engineering envelope" that is
>part of the design specification of another physical thing that has an actual
>measurable operating temperature. So it is a temperature and it is a property
>- it's just not directly associated with the physical thing that has an
>operating temperature.
> (01)
What is in a name? The problem is to write a razor. If a property has
characteristic X, it is indirect. And 15926 talks around it. It is not
clear that a "direct" property is required to be "intrinsic" -- a
property that doesn't vary with position or use or history (but that
gets into temporal issues). And it is not clear that "indirect"
properties are required to be "accidental" -- related to the appearance
of the thing in a role or situation. (02)
These "indirect properties" are commonly modeled as "attributes" of
things. Some of them are clearly accidental properties that are
assigned to a usage of the thing. The problem is that a property like
"maximum operating temperature" may be viewed as "intrinsic" if it means
the temperature beyond which the device will cease to operate. But the
same "property" may actually be stating a "rule" that is applied to the
device in a given usage, or a recommended rule of thumb for use of the
device. It doesn't mean that the device will cease to operate, it means
the device is likely to exhibit undesirable behaviors/properties if it
operates above that temperature. This agrees with Bill's
characterization as "part of the engineering envelope. From MY
ontological perspective, a rule is not a property; it is a rule. In the
business rules jargon, we are distinguishing a 'necessity' (an invariant
property) from an 'obligation' (an imposed constraint). (03)
Put another way:
Thou shalt not kill
is a rule, even if it is stated as the indirect property:
Thou.maximum-allowable-murders = 0 (04)
-Ed (05)
--
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 (06)
"The opinions expressed above do not reflect consensus of NIST,
and have not been reviewed by any Government authority." (07)
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