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Formalizing testSubject

From: Sean B. Palmer <sean@mysterylights.com>
Date: Sat, 2 Mar 2002 23:34:59 -0000
Message-ID: <00fc01c1c242$e0aabb00$b1560150@localhost>
To: <w3c-wai-er-ig@w3.org>
In EARL, the TestSubject is the thing being evaluated. There are two
requirements for identifying test subjects in EARL: a) we must be able
to refer to anything, and b) we must be very clear about what is being
identified. Examples of things that we may want to evaluate in EARL

   * A web page http://example.org/ on a particular date
   * A part of a web page - just an element, or a few elements
   * An accessibility tool, or a User Agent

This much we already know. In EARL 0.95, sometimes we have a necessary
level of indirection. For example, if you want to point to the page
http://example.org/ as it was on 2002-03-02, you can't just do
something like:-

   <http://example.org/> earl:fails :SomeTest; earl:date "2002-03-02"

because you'll lose the date information on merging. So instead, we
create a new thing - bNoded, or with a URI - something like [
earl:testSubject <http://example.org/>; earl:date "2002-03-02" ] .
This can be read as "a thing which is the web content at
http://example.org/ on the date 2002-03-02". In fact, there is some
information left out there. We don't really know that we're evaluating
a bit of WebContent at all...

   [ a earl:WebContent; earl:date "2002-03-02";
      earl:testSubject <http://example.org/tool> ] .
   [ a earl:Tool; earl:date "2002-03-02";
      earl:testSubject <http://example.org/tool> ] .

In this case, it's clear(er) what's being evaluated. In the top
example, we're evaluating the documentation for the tool, and in the
bottom example we're evaluating the tool documented at
http://example.org/tool. Unfortunately, there's no way that we can
either a) force people to use a type arc, or b) deduce what the author
of the URI *means* by it, unless they have stated that at the resource

So there's a problem there - ambiguity. I previously resolved [1] to
clear this up by introducing two new properties that would take the
place of testSubject: earl:reprOf, and earl:documentation. For example
(now assuming an EARL 1.0 namespace):-

   [ earl:reprOf <http://example.org>; earl:date "2002-03-02" ] .
   [ earl:documentation <http://example.org>; earl:date "2002-03-02" ]

rdf:type arcs aren't strictly necessary here since we know that the
domain of earl:reprOf is earl:WebContent, and that the domain of
earl:documentation is a union of earl:Tool and earl:UserAgent.

But it isn't necessary that we deprecate testSubject if people want to
include it; we can rely on people using rdf:type to tell us the kind
of content (as we do in EARL 0.95). A schema snippet for this is at

So there's a choice for EARL 1.0:-

   a) Use testSubject and not reprOf/documentation.
   b) Let people choose: testSubject or reprOf/documentation
   c) Use reprOf/documentation and not testSubject

Option a will depend upon people including an rdf:type arc, option b
may do if they choose to use testSubject, and the latter option will
not rely on rdf:type at all since the domains will take care of it.

There are also some issues about identifying bits of representations
etc., but that's not strictly a part of this debate, IMO.


[1] http://lists.w3.org/Archives/Public/w3c-wai-er-ig/2001Dec/0018
[2] earl:TestSubject rdfs:subClassOf
        [ daml:onProperty earl:testSubject; daml:cardinality "1" ] .
   earl:reprOf rdfs:subPropertyOf earl:testSubject .
   earl:documentation rdfs:subProperty earl:testSubject .

Kindest Regards,
Sean B. Palmer
@prefix : <http://purl.org/net/swn#> .
:Sean :homepage <http://purl.org/net/sbp/> .
Received on Saturday, 2 March 2002 18:34:43 UTC

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