Re: URN Usage

Richard Wiggins <WIGGINS@msu.edu> Fri, 17 September 1993 06:36 UTC

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Date: Fri, 17 Sep 1993 00:07:19 -0400
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From: Richard Wiggins <WIGGINS@msu.edu>
Subject: Re: URN Usage
To: "William A. Weems" <wweems@oac3.hsc.uth.tmc.edu>, Uniform Resource Identifier discussion <uri@bunyip.com>
In-Reply-To: Your message of Thu, 16 Sep 1993 15:38:18 -0500

>  > a) we assign a single URN to this (and pass it around with
>  > attribute information to distinguish the variant to choose) or
>  >
>  > b) assign a URN to each of the variants, with the attribute information
>  > telling us about the document we have.
>
>  I agree with Marc Andreessen that "a)" should be the choice since an
>  information seeker wants "to look for intellectual property on the
>  network, not 'Gif images' or 'JPEG images'". "The mechanics of which
>  file format the intellectual property is in is largely irrelevant..."

This is all fine in principle, but there are situations in which the
exact mechanics of the file format could be *extremely* relevant. If Dr.
Weems publishes some medical images at a high resolution and color depth
as GIFs, and I "mirror" them after some translations as highly
compressed JPEGs, the "intellectual content" may be the same in theory,
but some key elements of the images may be missing.

Of course, we run that risk anyhow due to the huge variations in
displays on our desktops. If those GIFs are 24 bit and my PC is garden
variety VGA, what I see will be different than what the author/publisher
sees. But if we accept by default the idea that a transformed version of
the same image *is* the same image for the purposes of URNs, I worry
that we're asking for all sorts of trouble.

At the Columbus IETF I recall Cliff Lynch pointing out that publishers
assign different ISBNs to a title that comes out in paper and cloth --
same "intellectual content" but different format. Now that may just be
to provide separate handles for ordering -- but it also makes sense when
you think about the text and diagrams being smaller, durability, etc.

Maybe the answer is that Dr. Weems gets to call the GIF and the JPEG
the same URN if he produced them, but anyone doing a transformation
outside his control must use a distinct URN?

/Rich Wiggins, Gopher Coordinator, Michigan State U

PS -- Medical images make a particularly interesting example here. I've
heard that doctors insist on the absolutely highest resolutions possible
for digitally handled images -- that speck you don't see could be
significant. Related digression: I've toured a medical facility where
digital MRI images are printed onto conventional X-ray film, 'cause the
docs' eyes are trained to look at those films up on the traditional
lighted wall panels. Sometimes the medium is *very* important...