This is a brief note on the above topic. I'm sending it to the meta2 list
rather than to one of the numerous working group lists as it has general
relevance, though it is especially related to the work of the Data Model
and Sub-elements working groups.
1. Qualifiers at Canberra
---------------------------
At Canberra we agreed to divide the Qualifiers into:
(a) Language
(b) Scheme
(c) Type (aka Sub-element Name)
For details, see "The 4th Dublin Core Metadata Workshop Report" (at
http://www.dlib.org/dlib/june97/metadata/06weibel.html).
This so exhausted us, we didn't have the time to discuss what constitues a
legal Type/Sub-element from a *topological* or *data model* point of view.
We did, of course, discuss legality from a *semantic* point of view, in
particular the "... criterion of a sub-element narrowing the semantics
of the element which it modifies".
2. Qualifiers at Helsinki
---------------------------
Following a day during which a lot of time was lost due to different groups
using the same word ("record") to mean different things, Stu asked us not
to use the word "qualifier", but to spell out *which* qualifier we are
talking about. The aim was to improve communication, not to ban future use
of the word "qualifier".
3. Qualifiers since Helsinki
------------------------------
The Language and Scheme qualifiers may turn out to be generically applicable
sub-elements for which we have devised a minimised representation in HTML.
This affects their representation in RDF and is one of the questions before
the Data Model working group.
Sub-elements are, from a data model point of view, more difficult, as they
have been, unintentionally, abused. An example of a sub-element which does
not fit any plausible data model is (please forgive my syntax):
DC.Creator.PersonalName="Misha Wolf"
DC.Creator.PersonalName.Address="85 Fleet Street"
Another very dodgy example is:
DC.Date.Created="1997"
It is my view that the above result from a desire to, *at all costs*,
minimise the amount of typing required to enter the metadata manually and
that the "correct" metadata would look rather like this:
DC.Creator.Name="Misha Wolf"
DC.Creator.Address="85 Fleet Street"
DC.Creator.Type="Person"
and:
DC.Date.Value="1997"
DC.Date.Type="Created"
Obviously, one could minimise DC.Creator.Name to DC.Creator and
DC.Date.Value to DC.Date. I have no problem with that.
Note that the sub-element called "Type" is not the same thing as the
qualifier we previously called "Type" and now call "Sub-element". I know
it's confusing. Let me give a less confusing example. At Helsinki we
agreed on two sub-elements for DC.Relation, namely:
DC.Relation.Type
DC.Relation.Identifier
In this example, it is clear that "Type" refers to a type of Relation.
Similarly, in the previous examples, "Type" referred to a type of Creator
and to a type of Date, respectively.
All of this is much clearer when written out using XML (no, this isn't RDF):
<DC:Creator>
<Name>Misha Wolf</Name>
<Address>85 Fleet Street</Address>
<Type>Person</Type>
</DC:Creator>
<DC:Date>
<Value>1997</Value>
<Type>Created</Type>
</DC:Date>
<DC:Relation>
<Type>Some-relation-type</Type>
<Identifier>http://www.somewhere.org/abc</Identifier>
</DC:Relation>
You can now add Scheme information, if required:
<DC:Date>
<Value>1997</Value>
<Scheme>ISO-8601</SCheme>
<Type>Created</Type>
</DC:Date>
and even:
<DC:Date>
<Value>1997</Value>
<Scheme>ISO-8601</SCheme>
<Type>
<Value>Created</Value>
<Scheme>DC:DateType</Scheme>
</Type>
</DC:Date>
and:
<DC:Creator>
<Name>Misha Wolf</Name>
<Address>85 Fleet Street</Address>
<Type>
<Value>Person</Value>
<Scheme>DC:CreatorType</Scheme>
</Type>
<Role>
<Value>Something-or-other</Value>
<Scheme>AAT-POR</Scheme>
</Role>
</DC:Creator>
Ooops! I just remembered saying it was a brief note, so I'd better stop.
---------------------------------------------------------------------------
Misha Wolf Email: [log in to unmask] 85 Fleet Street
Standards Manager Voice: +44 171 542 6722 London EC4P 4AJ
Reuters Limited Fax : +44 171 542 8314 UK
---------------------------------------------------------------------------
12th International Unicode Conference, 8-9 Apr 1998, Tokyo, www.unicode.org
7th World Wide Web Conference, 14-18 Apr 1998, Brisbane, www7.conf.au
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