Re: [xml-dev] The purpose of a namespace URI is ...

[Liam R E Quin <liam@w3.org>]

On Sun, 2012-12-02 at 14:18 -0500, John Cowan wrote:
> IMO the true error was to identify URIs with system ids rather than
> public ids.  If you had said that a system id has only local meaning (as
> in SGML) whereas a public id could be either a URI or an FPI, public ids
> would have continued to be extremely useful and w3.org wouldn't be being
> hammered by requests for various DTDs.

That could be.

 "what might have been is an abstraction /
  remaining a perpetual possibility / only in a world of speculation."

But I'm not convinced: public identifiers need indirection, and if you
have indirection you can ue indirection for the system identifiers too.

The contribution of public ids was their structure, and the idea of
giving something a name, not the fact that they didn't actually work :-)

URIs, however, have not the structure (language, version, issuing
authority, purpose) that's an important part of PIs.

Using a urn: public-identifier as a namespace identifier doesn't get you
anywhere further, since XML systems don't go peeking inside, and treat
the public identifier as opaque.

Liam

-- 
Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
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