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PIs considered harmful Was: XML-SW, a thought experiment

From: Tim Berners-Lee <timbl@w3.org>
Date: Tue, 12 Feb 2002 15:03:28 -0500
Message-ID: <016c01c1b400$56af4010$aa01a8c0@CREST>
To: "'www-tag'" <www-tag@w3.org>, "Elliotte Rusty Harold" <elharo@metalab.unc.edu>
imho

----- Original Message -----
From: "Elliotte Rusty Harold" <elharo@metalab.unc.edu>
To: "'www-tag'" <www-tag@w3.org>
Sent: Thursday, February 07, 2002 7:51 AM
Subject: RE: XML-SW, a thought experiment


> At 10:01 PM -0800 2/6/02, David Orchard wrote:
> >Tim,
> >
> >This is really great stuff.  While I think that PIs should also be lopped
> >off,
>
> I wouldn't. PIs are quite useful in practice. Eliminating them would
> hurt way too much. It is useful to be able to step out of the markup
> for processor-specific uses like PHP and stylesheets.

PIs are indeed "useful in practice".  However, I feel they are harmful
because they bypasss all the extensibility power one has with namespaces
to make well-defined extentsions.

PIs also add a barnacle onto the XML syntax which it really doesn't need.

The idea of namespaces is that you can use one to define a new
element to do just what you wanted to do with the PI, but you give
it a URI name, and allow possibilities such as using existing tools
for parsing and test for and converting them and so on.
What is there which stops you using an element?

PIs are in concept a significant security liability, because different
processors will
process them differently, and so one will be able to make a document
wheich will seem one thing in one case and another thing in another
case, without the XML system being offically aware of it.

I would agree with David and hope that PIs would be eliminated as soon as
possible.

Tim
personal opinion
Received on Tuesday, 12 February 2002 16:40:20 GMT

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