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   RE: [xml-dev] A thought on XLink in PIs for processing directives

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Most of that is spilt milk now.  OTOH, PIs are open 
to those who want to develop alternatives to specs 
and still use XML.  It is a very neat feature from 
that viewpoint.

PIs were heavily criticized in days of olde as 
a way to pollute content.  In effect, they were 
a way to avoid precisely that.  But those who 
used them were sidestepping the idea that all 
systems should interoperate based on a formal 
public declarations.  That is the One World System 
viewpoint.  It is seductive somewhat like a 
one world religion or government but inimical 
to the very idea it originates in:  the ability 
to create information free of local system 
constraints.  Ultimately, the information owner 
has to choose.  XML, the W3C, etc., should only 
have a limited ability to control those choices 
and then only insofar as a system definition 
enables interoperation without unduly limiting 
choice.   The W3C and XML are there to enable potential; 
not control markets.

The owner has to choose wisely.  As noted often 
here, XML is as underpowered as it is because 
a syntax spec enables interoperability right 
to the edge of limiting other choices.  Otherwise, 
one becomes a wraith in the tunnels muttering 
"My precious!" after surrendering all options 
to the FrameworkFromMordor.

len orc

-----Original Message-----
From: Jason Diamond [mailto:jason@injektilo.org]

> PIs were a common means in SGML systems to create links.
> IDEAS/IADS worked like that originally.  It was the
> interpretation of some that links are not really content,
> they are a process/function.   It is a theoretical issue at the
> very heart of darkness for hypertext systems.

To me, it seems obvious that the xml-stylesheet PI is not content since it's
only allowed in the prolog of an XML document (before the document element).
The xsi:schemaLocation attribute, on the other hand, is content (although it
will most likely be ignored by processors other than schema validators).

Unfortunately, just like namespace declarations, xsi:schemaLocation can
appear on any element in an instance document--though it must appear before
an element or attribute is encountered in the namespace described by the
schema found at that location. Personally, I agree with Michael and would
have rather seen something like an xml-schema PI (or a more generic xml-link
PI) in the prolog--one for each namespace the document contained. This keeps
the processor-specific data out of the document and makes it really easy to
see exactly what the document contains from a really high-level point of

<?xml-schema namespace='http://example.org/'
href='http://example.org/schema.xsd' type='application/xsd+xml'?>


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