[entity-resolution] Re: uri vs. system confusion

[Mark Johnson <mrj@debian.org>]

John (and others),

(BTW, this discussion started with my post [1] to the
entity-resolution-comment list.)

After reading the relevant section of the XML spec (4.2.2), I still
find redundancy in using both system-based and uri-based elements. The
problem lies in the fact that the XML spec defines 'SystemLiteral' as
a URI, thereby _not_ limiting its form to that of a URL.

Furthermore, (external) ENTITY declarations and NOTATION declarations
(XML 4.7) both make use of the form of an ExternalID, i.e. a
SystemLiteral.

And, as mentioned above, the SystemLiteral is defined as a URI (not a
URL). From section 4.2.2 of the XML spec:

   [Definition: The SystemLiteral is called the entity's system
   identifier. It is a URI reference (as defined in [IETF RFC 2396],
   updated by [IETF RFC 2732]), meant to be dereferenced to obtain
   input for the XML processor to construct the entity's replacement
   text.]

Since: 

a. all relevant non-public references are required to be
   SystemLiterals, and,

b. all SystemLiterals are URIs,

Then:

1.  all SYSTEM ids should be treated as URIs, and nothing less.

Therefore all SYSTEM references should make use of the uri-based
elements - and not the system-based elements.

Furthermore, use of uri, rewriteURI, and delegateURI in lieu of the
system, rewriteSystem, and delegateSystem elements seems to be
consistent with Production 75 of the XML spec.

So I don't see why the system-based elements are needed at all.

   (I can't help but wonder I'm missing something here, as I now feel
    like I understand the issue...)

Clarification, anyone?

Thanks,
Mark

[1] http://lists.oasis-open.org/archives/entity-resolution-comment/200302/msg00000.html

On Friday, February 7, John Cowan wrote:
> Mark Johnson scripsit:
>
> > [...] I'm still a bit confused about the distinction between the 
> > uri-based elements and the system-based elements.
> 
> In a word, the system-based elements are used only when an XML parser is
> processing ENTITY and NOTATION declarations in the DTD.  The URI-based
> elements are used for all other lookups.
>
>
> > B. [...] another implied usage is IMO that SYSTEM Ids get remapped
> >     _only_ via a <rewriteSystem> element, and never via the 
> >     <rewriteURI> element. (This despite the fact that all system 
> >     identifiers are URIs.)
> > 
> >    Is this the intended usage? 
> 
> Yes.
>
> >     Does the reason for using <rewriteURI.../> have something to do
> >     with the fact that the stylesheet URI does NOT appear in the XML 
> >     document, and is therefore not restricted by the ExternalID as
> >     SystemLiteral constraint as per the XML spec? Again, any 
> >     clarification here would be greatly appreciated..
> 
> Just so.

-- 
_____________________________________
Mark Johnson        <mark@dulug.duke.edu>
Debian XML/SGML     <mrj@debian.org>
Home Page:          <http://dulug.duke.edu/~mark/>
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