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This message is particularly targeted at the folks who will attend the
meeting at Harvard about METS extension schemas next week, although it may
be of interest to others.  In preparation for this meeting, and to set
ourselves up for our next round of project work, the LC AV prototyping
team has been rethinking our extension schemas. We have been inspired by
our colleagues in the Harvard Library digital initiative group and by the
team from Michigan State.  (Thank you!)

Our ideas are laid out a revised set of web pages:
http://lcweb.loc.gov/rr/mopic/avprot/metsmenu2.html

What is different?  The principal changes have to do with the
"file-techy" extension schemas. Our proposal features four file-specific
schemas: audioMD, imageMD, textMD, and videoMD. In their adjusted form,
these are now intended to serve in BOTH the techMD socket and the sourceMD
socket. They work in sourceMD when the source is a digital file, e.g., a
file being migrated into a new format. The proposal also features three
other schemas (audiophysrcMD, imagephysrcMD, and videophysrcMD) for use
when the source is a physical (tangible) item to be reformatted.  Don't
forget that physical/tangible items may be digital or analog, e.g., an lp
as compared to a CD, or a DigiBetacam tape as compared to a BetacamSP.

The advantage of the proposed approach is that a single schema set for
files will serve in two locations.  And the schemas will be more
streamlined than our old sourceMD schemas, since the sometimes-cumbersome
metadata associated with physical items is placed in separate schemas of
their own.  One drawback of the approach, however, is that ten
file-specific fields that appear in the METS primary schema must be
repeated in the extension schemas in order to provide a full set of data
when a digital file is the source for a new file.

If you studied our last versions of audioMD and imageMD, you will see that
we have adjusted our set of attributes.  Our MSU colleagues advised us to
make our image attributes conform more fully to the NISO recommendation,
while Dave Ackerman at Harvard guided us to add audio attributes.  Dave is
active in the Audio Engineering Society metadata effort.

During this period, we have also continued to wrestle with descriptive
metadata as it pertains to our projects.  You will see a very provisional
placeholder in the web site.  We are also playing with some ideas for
digiprovMD but have nothing at the site yet.

Since the schemas proper are still getting drafted, most of the detail in
the current web presentation takes the form of lists of attributes;
usually, a data dictionary.  The data listed there is what will be folded
into our next set the schemas.

This and alternate ideas will be grist for next week's meeting.  Comments
are welcome.

Carl Fleischhauer
Library of Congress