This is the first of what I hope will be a series of messages from the LC
audio-visual team pertaining to details of metadata. My colleagues and I
are trying to work thru some stuff one chunk at a time.
Today's msg is sent with Jerry in mind. At the Pittsburgh meeting we
discussed increasing the number of elements in filegrp to permit folks to
produce streamlined METS documents by omitting TECHMD but not lose
critical file-level data. I went back to our "all files" element set to
see what we might nominate for filegrp and what we would agree to leave in
I studied the METS gamma version. Assuming that the "date" ("event"?)
element in filegrp can have attributes (e.g., created, modified,
accessed), the following elements are the ORPHANS left from our "allfiles"
schema. The names and definitions below are taken from our relational
database data dictionary; in XML, things like "checksum" would be elements
with attributes, natch.
-- byte_order: The order of bit significance in a byte from left to
right. (Big and little endian, Motorola vs. Intel, etc.)
-- the checksum trio:
-- -- checksum_value Checksum value of the file, e.g.,
-- -- checksum_type Type of checksum algorithm employed, e.g., MD-5,
RSA-MD4, HC Checksum algorithm, etc.
-- -- checksum_datetime Creation date and time of the checksum, e.g.,
1997-04-22 (date only), 1997-04-22T19:20+01:00 (full expression), etc.
-- security: Type of encryption or other security used in the file, e.g.,
symmetric, assymetric, RSA encryption, Rabin encryption etc.
-- watermark: Type of watermark used in the file, e.g., Digimarc,
Giovanni, Alpha-Tec, StirMark, etc. SBCS(255) NONE
-- use: Use of the file, e.g., [Library of Congress terms, displayed for
end-users] Master, Service High, Service Low, Preview.
QUESTION 1: Are any of these nominees for filegrp or shall we agree to
leave them in TECHMD?
QUESTION 2: If this whole bunch should stay in TECHMD, should we add them
as a block to all four extension schemas or continue to have a separate
"allfiles" schema? This is asked to the METS group because we share an
interest in building an application profile that we all like.
PS: There is also an orphaned field we have called either
compression_codec or compression_method. For this, we were not thinking
of the value "MP3" but rather "Frauenhofer" or "Sorenson" for the specific
coding algorithm used. I suppose something like this would also be useful
if you were anal enough to want to track the quantization tables you used
to make a JPEG file. My mood today is to leave this one in audio and
video TECHMD, and I plan to make it part of my coming dialog with our
colleagues at Michigan State. Interim comments are welcome, however.