# Re: Unresolvable URNs --> ISBNs (discussion, not resolution)

David Robison (robison@nwnet.net)
Tue, 22 Feb 1994 09:38:37 -0800 (PST)

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    Date: Tue, 22 Feb 1994 09:38:37 -0800 (PST)

    From: David Robison <robison@nwnet.net>

    Subject: Re: Unresolvable URNs --> ISBNs (discussion, not resolution)

    To: timbl@www0.cern.ch

    In-Reply-To: <9402211453.AA01922@ptpc00.cern.ch>

    Message-Id: <Pine.3.89.9402220944.H27291-0100000@norman.nwnet.net>

On Mon, 21 Feb 1994, Tim Berners-Lee wrote:

>
> David Robison <robison@nwnet.net> says:
> > A correction is in order here: ISBNs are not opaque. They are made up of
> > 4 discrete sections: the first represents language/country; the second is
> > the publisher number; the third is the book number (simply and ordinal);
> > the last digit is a check digit.
>
> What do you mean my "opaque"? They are used by most people without the
> knowledge that you have. They are pretty opaque to me :-)

Are you implying that not all people are librarians? ;-)

> When you order a book by ISBN, does the bookshop look up
> the list of publisher prefixes? Is there a resolution algorithm
> well defined?

There are directories of publishers with ISBN indexes (GK Sauer, Books in
Print), but I suspect many bookstores simply manage their stock using
ISBNs and don't care about the publisher until it comes time to reorder.
I think the only algorithm involved is the one that produces the check digit.

> An interesting point is that you can't determine where the boundaries
> lie between the fields. So the ISBN authorities can cook up
> flexible (classless a la CIDR) allocation spaces without worrying the man
> in the street. But as you say, they dropped it when it came to
> the fixed length. (They just chose 10**9 instead of 2**32 :-)
> I guess variable-length bar code technology wasn't there at the time.
>
> Tim BL

Perhaps if librarians, rather than pubishers, had cooked up the scheme it
would be (more) scalable.

David

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