On Mon, 22 Sep 2003, Ann Apps wrote:
> I wonder if the definition of 'related metadata' in the proposed
> abstract model needs to be extended. There seems to me to be
> some inconsistency in the document. At present it says:
>
> 'Related metadata: A metadata record that describes a resource
> that is related to the resource described by a DC metadata record'.
>
> Igmoring that definition for a moment, the words 'related metadata'
> imply to me several different things and I suspect people are using
> it to means all of these:
I'm not sure what 'people' you are referring to here? As far as I know,
the term 'related metadata' is *only* used in my draft document? Within
that document, it is used as defined (I think).
> (a) More metadata about a resource that there is no appropriate DC
> property for. Where metadata is encoded as XML the DC in XML
> guidelines give examples of this as 'mixed' metadata.
>
> (b) The same metadata as in the DC property fields, but encoded
> using metadata properties from a different namespace.
I'm not aware of 'related metadata' being used to mean either of these -
not in the abstract model draft at least.
> (c) A combination of (a) and (b).
>
> (d) Metadata about a related resource.
>
> (a, b, c) are in fact encodings of application profiles.
>
> I'm a bit unsure about (d). It implies I could include in a DC record
> for a journal article metadata about other articles that the article
> references, using dcterms:references. Doesn't this break the
> principle (1-1?) that a DC record for a resource should not include
> metadata for another resource?
No, it does not do this. Quite the opposite. One of the purposes of the
model is to make it clear that 'related metadata' is *not* part of the
abstract 'record' and that all the properties in the record *must* be
attributes of the resource being described. Hence the abstract model
completely endorses the 1:1 principle.
Now, it may be the case that a particular encoding of instance metadata
(e.g. the RDF/XML encoding) may embed descriptions of multiple resources
within a single instance document - but that is a syntax issue. But by
looking at the way a particular syntax implements the abstract model, it
is possible to see that the 1:1 principle is preserved in the abstract
model.
> Or is this document an attempt ot
> relax that rule, reflecting that in reality people are creating records
> that include related metadata?
Again, no. The abstract model tries to clearly separate out the
descriptions of different resources when more than one resource is being
described. That is the whole purpose of introducing the notion of
'related metadata'.
> Later in the Abstract Model, DCSV is defined as a labelled string,
> and that it should be treated as related metadata. This seems to
> be using 'related metadata' as in (a,b,c) in some cases. Period,
> Box and Point are giving more, or more precise, metadata about
> the resource itself not about a related resource.
Not really... period, box and point give 'related metadata' about three
related resources - a 'period in time', a 'box in space' and a
'point in space'. These three things might be fairly abstract concepts,
but they are nonetheless resources.
> The now defunct
> DCMICite was providing more metadata about the resource, for
> which there was no appropriate DC property, not metadata for a
> related resource.
I agree that the DCMICite proposal does raise a slight problem with my
definition of 'related metadata'. dc:identifier is something of a special
case. Because the value URI for dc:identifier is the URI of the resource
being described, if there is 'related metadata' associated with that
property, then is is metadata about the resource, and not metadata about a
related resource. This is also true for any element refinements of
dc:identifier. I need to think a bit more about this. I'm not sure how
best to handle it.
> Though the Vcard example is metadata about a
> related resource.
Correct.
> So does the Abstrat Model document also need to include
> something about mixed metadata / application profile?
I think it probably does - but not for the reasons you outline above :-).
My current plan is to re-draft the document with an initial section that
covers an abstract model for DCMI metadata (though I might label this an
abstract model for DC[MI] application profiles). This model will then be
refined into abstract models for qualified and simple DC. I think that
will make the model cover what you are suggesting here.
Andy
--
Distributed Systems, UKOLN, University of Bath, Bath, BA2 7AY, UK
http://www.ukoln.ac.uk/ukoln/staff/a.powell +44 1225 383933
Resource Discovery Network http://www.rdn.ac.uk/
|