RE: OWL 2.0 ...

Pierluigi,
 
Let me start with an excerpt from the book "Ontological Engineering" by
Asunción Goméz-Peréz, Mariano Fernández-Lopéz, and Oscar Corcho:
QUOTE
What are things? What is the essence that remains inside things even when
they change (changes in their color, changes in their size, etc)? Do
concepts (book, tree, table, etc) exist outside our mind? How can the
entities of the world be classified? These are some of the questions that
Ontology, the philosophy of being, has tried to answer for thousands of
years. In Ontology we can distinguish between essence and existence.The
essence of something is what this something is. However, an existence is to
be present among things in the real world. For instance, a centaur is half a
man and half a horse, so it has essence though it does not exist.
UNQUOTE

You wrote:
<PM> This strikes me as an exquisitely ontological, or if you prefer
domain-sensitive, determination
<HT> The data model of ISO 15926-2 is as generic as it can be and is NOT
domain-specific. The domain-specific aspects are introduced when linking it
to a particular vocabulary (we call it a Reference Data Library). If the
library is about medical classes, the information is about medical matters,
if the library is about real estate stuff, it is real-estate information.
How much more generic can you be? And what is wrong, in the context of OWL,
with being "exquisitely ontological"?
 
<PM> There are plenty of individuals (in the sense in which individuals are
in pricniple distinct from classes) that would not have spatio temporal
presence such as you describe. 
<HT> In our, and the above, meaning of "individual" ALL have spatio-temporal
presence. It is a matter of definition and paradigm. 
 
<PM> There can be abstract individuals that have no particular location,
though perhaps a "lifetime": ordinary examples would be, under plausible
assumptions, Beethoven's 5th symphony and the "Crusoe." 
<HT> This proves my point: you don't make a difference between Beethoven's
5th Symphony as (in our terminology) a class_of_activity and as an activity.
The latter happens at a particular evening in, say, the Scala of Milano, and
is a member of the class_of_activity "Beethoven's 5th Symphony", together
with all the other performances in the past, present, and future.
 
<PM> There can be individuals that have perhaps location in abstract space,
but no lifetime: the Equator, or the North Pole.  All this might be in
dispute, of course.  
<HT> The North Pole and the Equator exist in real space. I don't think that
Robert Peary's expedition in 1909 travelled to something that was in
abstract space. In our definition the North Pole is a spatio-temporal
individual that is a "feature" of the globe (like a nose is a feature of a
face), and it is classified with a class that has certain criteria for being
a North Pole (mind you, the North Pole isn't at the same location all the
time).

<PM> The point is I don't think this belongs in a language's specification. 
<HT> Not if you deliberately want to limit the expressivity of that
language.
 
Regards,
Hans
____________________________
Hans Teijgeler
co-author of ISO 15926-2 <http://www.infowebml.ws/ECM4.5/ECM4.5.html> 
author of ISO 15926-7
website www.InfowebML.ws <http://www.infowebml.ws/> 
e-mail hans.teijgeler@quicknet.nl
phone +31-72-509 2005