Re: Classifications - response to Martin Bryan

[Martin Bryan <mtbryan@sgml.u-net.com>]

Len

> Now Martin asks how one might create a new classification scheme, EU-1995,
> that isolates the countries of Europe that were registered as member
states
> of the European Union (EU) in 1995.

I wasn't thinking of creating a new classification scheme, but of further
qualifying an existing one. The problem is that there is a missing level (or
set of levels) in ISO 3166. It fails to recognized that between Continent
and Country there is a "Political Bloc" unit.  As you pointed out this does
not have clear boundaries. For example, the EU is likely to be expanded to
include both Turkey and Israel. The first straddles two contintents, the
second is not even in the same continent. As you pointed out there are often
not clearcut boundaries between things (which continent does Greenland
belong to? Is it a country? Is it a region of Denmark?).

But at the same time I do not want my scheme to have to create new
classification nodes for the already registered concepts of Europe and the
individual countries therein. I want to reuse the same nodes, and have
people be able to see that country X is a member of the Europe Class in the
IS0 3166 classification, and of the EU-1995 class of EU Member States and
the NATO-2001 class of NATO members, and a member of the UN.

You say
>These new nodes might
> use the same 2-character identifiers and the same English spellings of
> names to identify the countries, but they are nodes of a different
> classification scheme, not some revision of the existing
> "Continent/Country" 2-level scheme.

But do they need to be defined as separate ClassificationNodes for each
scheme?

> The assumption here is that a classification node takes on a life of its
> own and can participate in many different categories.

The real assumption is that one definition can have multiple uses. [If this
constitutes a life .... :-)]

>This could get very
> complex. Isn't this very much like a "Topic Map" where a bunch of topics
> get registered and then have associations with one another?

Funny you should say that to one of the editors of the Topic Map standard
:-)

>Nodes in a
> classification scheme are inter-dependent, e.g. if the scheme has a
> stability attribute of "Static" shouldn't all nodes in that scheme be
> static too?

Point me to a truly static scheme. ISO standard classification schemes are
reviewed every 5 years at a maximum. They are as stable as they come. What
you mean is "timestamped". This version of the classification scheme must
always be identifiable as the 2001 version of this scheme. What this implies
is that if a new version is defined then any existing ClassificationNodes
that are used in the next version will need to be redefined to be used in
the new version. Surely this is wrong.

> It would then be up to a user to be aware that two
> separate classification schemes may be required to classify a given
> repository item, e.g. Continent/Country may be one such scheme and
> Country/LocalPoliticalUnit may be another. Or LocalPoliticalUnit may be a
> collection of separate classification schemes, one for each country.

We need some way to tell users "this node appears in this set of
classification schemes, and is the starting point for this set of
extensions"

> For example, in the Continent/Country and Country/LocalPoliticalUnit
> schemes discussed above, I would favor the ability to create a new scheme
> Continent/Country/LocalPoliticalUnit that was defined via references to
the
> existing schemes without the need for re-creating nodes, even if the
> existing schemes were repository items in separate Registries! Such
> capability would be an upward compatible extension to what I'm proposing.

This is what I would ask you to acheive

Martin