Re: [xtm-wg] In the opera topic map, what is a "PSD"?

[Steve Pepper <pepper@infotek.no>]

At 11:21 12.05.00 -0700, Sam Hunting wrote:
>The subject line says it all. The "PSD" acronym doesn't seem to be
>expanded anywhere in the documentation.

Sorry. It stands for "public subject descriptor" -- i.e. a
standardized string, used as the value of a topic's "identity"
attribute, whose purpose is to establish (as unambiguously as
possible) the identity of the subject to which the topic
refers.

The current version of the opera topic map uses PSDs in three main
areas:

     (1) to identify base constructs (tt, at, ar, or, ft, fv, th)
     (2) to identify transitive associations
     (3) to identify countries and (some) cities

For (1) we want to identify topics that are used for typing
topics (tt), associations (at), association roles (ar), occurrence
roles (or), facets (ft) and facet values (fv), and also which ones
are there simply in order to be used as themes to define scope
(th). The reason we are doing this, is because in an editorial
environment, there is a need to be able to control what the base
constructs are that define the topic map's ontology: It's a bit
like (one) role of a DTD: to define the schema, the rules by which
the topic map itself must abide.

(2) is there because knowledge of which association types exhibit
the property of transitivity provides enormous inferencing power
to the topic map engine.

The idea behind (3) is that information about countries will be
required in many topic maps, so, in order to be able to modularize
and re-use (through merging), we need to identify subjects like
countries and cities.

The actual strings used are our own invention and are based on
the ontopia.net domain. If and when the XTM activity defines other
strings, possibly using a a different syntax, we will obviously
map to or convert to those.

Steve

--
Steve Pepper, STEP Infotek AS (+47 908 27246)


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