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Re: public/catalog [was: Re: ERB Decisions of March 26th]



Terry Allen wrote:
> 
> Let me say it another way.  User agents should not be required to
> support catalogues *or any other mechanism specified by XML*
> to resolve public identifiers.  There should be *no default
> assumed* by publishers.  That's hard to swallow, and most of
> this group is choking on it; ask yourselves whether you need
> a specified default mechanism to find a copy of Moby Dick;
> ask yourselves whether, had Melville's publisher specified a
> default mechanism (e.g., writing to the publisher's address),
> you should have to follow it today.

You never have to follow a default mechanism if you have a better
mechanism. That is why it is a default mechanism and not an exclusive
mechanism. I would rather that Melville had given the publisher's
address than nothing at all. If I was in enough trouble to need it, it
might be a better clue to where the data currently exists than nothing
at all.

Similarly, providing a catalog provides you with a starting point that
is at least as robust as a URL, and if you know a better way to find the
public identifier, you are encouraged to use it. Michael's current
proposed spec (which is newer than your message) is quite explicit about
this:

"XML processors may implement any mechanism they choose for resolving
public identifiers (i.e. finding a URL for some physical copy of the
object named). At user option, however, they must also support the
mechanism described in this section."

So your analogies of forcing booksellers to write letters to the
publisher of Moby Dick are inaccurate. Rather book authors are forced to
include the publisher's address in the front of the book in *case* the
bookseller has no better way of getting in touch with them. I think you
will agree that requiring a snail mail address in the front of a book is
not an onerous task, nor is requiring a base, primitive, system
identifier lookup mechanism within XML.

The advantage of requiring the address to be in the catalog rather than
in the document is that you don't have to change the document when files
move around the web.

 Paul Prescod


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