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Re: identify XHTML DTD by URI, not by FPI

From: Dan Connolly <connolly@w3.org>
Date: Tue, 15 Feb 2000 17:07:36 -0600
Message-ID: <38A9DC38.D1673E4E@w3.org>
To: Arjun Ray <aray@q2.net>
CC: www-html@w3.org
Arjun Ray wrote:
> 
> On Thu, 10 Feb 2000, Dan Connolly wrote:
> 
> >      <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"
> >                            "xhtml-basic10.dtd">
> >
> >       -- http://www.w3.org/TR/2000/WD-xhtml-basic-20000210/
> >
> > I don't believe it's in W3C's interests
> 
> That's becoming increasingly clear.
>
> > (nor the interests of the Web Community)
> 
> This isn't clear at all.

Would you please elaborate? How is it valuable to the web community
for W3C to issue Formal Public Identifiers in addition to
URIs that are guaranteed to be highly available and not reassigned to
other purposes?

> > to issue XML public identifiers,
> 
> There is no such thing as a 'XML public identifier' (unless NIH also
> includes comprehensive reinvention of terminology.)  I believe you're
> refering to Formal Public Identifiers.

Yes... thanks for the clarification.


> > and I don't know what way it would be "appropriate" to modify the
> > system identifier.
> 
> To reflect the reality of a mapping being convenient for operational
> purposes.  That's the fundamental distinction between PUBLIC and
> SYSTEM.   $system_id = $catalog{$public_id}

In what way is this distinction fundamental?

I can see where it's useful to be able to relate standard identifiers
to local identifiers by operational convention, but in those cases, it
seems just
as easy to do:
	$local_uri = $catalog{$standard_uri}

and even so, it doesn't seem fundamental: even the $local_uri is mapped
to filesystem, an inode, a block within the inode, and so on.

c.f. The Name Myth -- Axioms of Web architecture
http://www.w3.org/DesignIssues/NameMyth

> > Note that the popular mechanism for looking up FPIs in a local
> > catalog also works for URI system identifiers:
> >
> > "SYSTEM sysid1 sysid2
> > [...]
> > -- SP - Catalogs
> > http://www.jclark.com/sp/catalog.htm
> >
> > I wonder if that's included in the SGML Open TR... crap..
> > broken link: http://www.oasis-open.org/a401.htm
> 
> From:
> 
>   http://www.oasis-open.org/cover/sotr9401-a2.html

Ah! thanks for finding that for me. The oasis web site wasn't
very responsive when I went looking (I found out, by telephone,
that they've switched ISPs and are working out some kinks).

> 
> :  The SYSTEM keyword indicates that an entity manager should use the
> :  associated storage object identifier to locate the replacement
> :  text for an entity whose external identifier's system identifier is
> :  explicitly specified by the system identifier.
> 
> According to the TR, 'sysid2' is a "storage object identifier" and
> thus oridinarily a FSI (Formal System identifier.)

Umm... if I understand correctly, the bottom line is that yes,
SGML Open Catalogs work (in the sense of implementation and
specification) just as well for URIs as for FPIs.

i.e. there would be no loss in functionality in changing from:

PUBLIC "-//W3C//DTD XHTML Basic 1.0//EN"                      
"xhtml-basic10.dtd"

to:

SYSTEM
"http://www.w3.org/TR/2000/WD-xhtml-basic-20000210/xhtml-basic10.dtd"                      
"xhtml-basic10.dtd"

in
"B.1. SGML Open Catalog Entry for XHTML Basic"
http://www.w3.org/TR/2000/WD-xhtml-basic-20000210/#a_catalog

-- 
Dan Connolly
http://www.w3.org/People/Connolly/
Received on Tuesday, 15 February 2000 18:07:43 GMT

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