[sc34wg3] Subject Locators

Lars Marius Garshol sc34wg3@isotopicmaps.org
Mon, 13 Jun 2005 20:44:14 +0200

* Jan Algermissen
| Because on the web you only have a single addressing context. Saying
| that some URI is a subject locator does not imply that the resource
| the URI points to is document-like at all. IOW, you cannot alter the
| underlying definition of URI by introducing additional addressing
| semantics. 

Of course! But this isn't about the URI, only about the *use* of the
URI. So the URI


references the same resource regardless of whether I use it as a
subject locator or as a subject identifier, and it's perfectly
acceptable to use it as both things in the same topic map. The URI
continues to reference just a single resource throughout this entire

A topic that uses it as a subject locator represents one thing (the
bits&bytes representation retrieved over HTTP), while a topic that
uses it as subject identifier represents a completely different thing
(the concept described in the page).

It's true that in everyday usage we tend to talk about subject locator
vs identifier in a way that makes it *sound* as though something is
happening to the URI, but that's not the case. It's just a compressed
mode of expression used between people who know what is really going

| You seem to think that using a URI as a subject locator gives you
| the ability to say: "this URI refers to a some concept that is in
| fact a document (bits and bytes)."

No, no, no. This is about what each topic map is *using* the URI to
do. That's something else.

Let me try to put it another way:

  - when you put the URI into the [subject locators] property, you are
    saying: I'm referencing this resource directly, but

  - when you put the same URI into the [subject identifiers] property,
    you are saying: I'm referencing *another* resource indirectly via
    this one

(As in <URL: http://www.w3.org/TR/webarch/#indirect-identification >)

Does that help?

Lars Marius Garshol, Ontopian         <URL: http://www.ontopia.net >
GSM: +47 98 21 55 50                  <URL: http://www.garshol.priv.no >