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RE: How did "public identifier" get its name...

• To: 'Norman Walsh' <ndw@n...>, xml-dev@l...
• Subject: RE: How did "public identifier" get its name...
• From: "Bullard, Claude L (Len)" <clbullar@i...>
• Date: Thu, 31 Jul 2003 08:52:54 -0500

Yes.  The DOCTYPE used where the PUBLIC and SYSTEM identifiers 
are paired works marvelously well.   
 
I think it an issue of clarity.  If the user wants to be 
clear that no dereference operation is directly intended, 
use the public identifier.  If one wants to be clear that 
a dereference operation is intended even if future, use 
the system identifier.  If one needs both, use both 
or implement indirect addressing such as XML catalogs.

The problem of the Universal Identifier concept is that 
it assumes the web is the universe and vice versa.  It 
builds unreliability into the system.  Definitions that 
include the term 'universal information space' are silly.

len

From: Norman Walsh [mailto:ndw@n...]

/ "Bullard, Claude L (Len)" <clbullar@i...> was heard to say:
| Yes, there are implementations that map PUBLIC identifiers to 
| web identifiers.  For them that needs 'em, use 'em.  OTW, not. 

XML Catalogs, for example. And vice versa, RFC 3151 for example.

| If you are using the web as your mass storage device, you 
| don't need public identifiers for much if anything although 
| they are still used in DOCTYPE declarations.

One of the nice features of DOCTYPE declarations that I haven't seen
mentioned very often is the fact that they allow you to specify both
a name and an address. So Joe User sends me

  <!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
                    "file:///c:/path/to/some/place/docbookx.dtd">

and it *just works* on my machine because I can map from the public
identifier to a local identifier.

  <!DOCTYPE article SYSTEM "file:///c:/path/to/some/place/docbookx.dtd">

is just about useless on anyone's system except Joe User's. As is

  <article xsi:schemaLocation="file:///c:/path/to/some/place/docbookx.xsd">

but, alas, there's no obvious way to specify the public identifier in XSD.
You can use RFC 3151, but no one does.

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