Hi,
For the purity of the data model the mdRef element should only contain
information about the reference itself and not about the target of the
reference (the file). An ADMID would contain administrative metadata for
the reference as e.g. lifetime of a reference etc... I am not sure we
need ADMID for mdWrap.
If we would like to store administrative for the referenced file, we
need to define this file first. Currently there isn't any element which
defines metadata files.
I am not sure where we could define such a file. In theory the file
section seems to be a good place, though my understanding always was
that files in the file section are just representing the content. The
mdRef would link to a <file> element in the fileSec, which then points
out to the actual file. However, we might even want to think about an
additional section for this.
Unfortunately the way METS references metadata records is not very well
modelled. METS uses a single element mdRef for two purposes:
1) it defines a metadata record (as the mdWrap element does)
2) and provides a link to the record using xlink attributes.
I believe METS should define metadata records very similar to files and
provide two different elements for the definition and the link. But this
might require a much more strict definition what a metadata record and a
manifestation of a metadata record is. Just to clarify what I mean with
manifestation of a metadata record:
A metadata record as an abstract object containing the semantical
information to describe another object. It's manifestation uses a
certain format to serialize this information. A metadata record may have
a DC manifestation a MODS manifestation, a MARC21 manifestation.....
Each manifestation can be stored in one or more locations.
The METS model does not differentiate between the metadata record
manifestation and its location. I am also not sure if METS defines a
metadata record. In theory a dmdSec might contain more than one metadata
record as its mdWrap and mdRef elements may contain metadata records
with very different semantical information (and not just in different
formats).
The question how METS handles metadata records becomes important if METS
is used in a preservation environment. A preservation system should
(well, probably must) regard each metadata record as an object in its
own right. A metadata record is usually managed independently from the
content. It may be refined (add new fields) or migrated.
In this case additional (preservation) metadata need to be stored for a
metadata record. METS is currently not able to store metadata records
for metadata records. I am also not sure to which METS element an
appropriate preservation metadata record should be attached. The dmdSec?
The mdWrap/mdRef?
I am also not sure what kind of metadata Robin wants to store - seems it
is neither on metadata record nor on metadata record manifestation level
but on the actual storage level.
I think this issue is slightly broader than just adding an ADMID
attribute. Might even be that we should get rid of the FILECORE
attribute as well ;-)
Ciao
Markus
-----Original Message-----
From: Metadata Encoding and Transmission Standard [mailto:[log in to unmask]]
On Behalf Of Robin Wendler
Sent: 14 May 2009 15:45
To: [log in to unmask]
Subject: [METS] ADMID on mdRef
Hi, all --
We'd like to include in METS documents the administrative and
technical metadata associated with an mdRef'd metadata file. Right now,
it looks like there is no ADMID attribute on mdRef. One would have to
use the ADMID on the encapsulating element (e.g. techMD, digiprovMD),
which may not be appropriate, since the linked ADMID would refer not to
the encapsulating element as a whole, but rather to the specific file
within the mdRef.
The METS Board did add the FILECORE attribute group to mdRef, which was
a recognition that one might need to record more information about the
ref'd file.
Adding ADMID would be a logical next step to enable folks to manage
metadata files similarly to the way they manage content files.
Any thoughts? Thanks,
--Robin
Robin Wendler
Harvard University Library
Office for Information Systems
90 Mt. Auburn St.
Cambridge, MA 02138 USA
617-495-3724 (W)
[log in to unmask]
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