<?XDEV?> and BEHAVIOR: a meta-proposal and a proposal

David G. Durand dgd at cs.bu.edu
Mon Nov 17 17:28:35 GMT 1997

I want to respond to the "meta-proposal" a bit, because I disagree with
some of the axioms, and the proposed procedures. I don't have time or
energy right now to respond to the specific proposal, though I may well do
so later (based on my own, somewhat divergent, axioms).

At 6:45 PM -0000 11/15/97, Peter Murray-Rust wrote:
>  <AXIOM>In any of these cases there is no general solution acceptable to
>  </AXIOM>
>  <AXIOM> If no attempt is made to address these problems we shall either
>end up with a Babel of incompatible solutions, or wait feebly for some
>powerful autonomous entities to dictate a limited set of actions.
>  </AXIOM>

Not necessarily. In fact, for many problems the correct response is to
ensure that the stylesheet ans processing specification langauges can
_implement_ each of the specific solutions desired, _without_ forcing the
specific solutions on whihc divergence of opinion may exist. More on this
with the "PI" axioms.

>  <AXIOM> We have to be careful to avoid the 'only processable with
>software X' syndrome</AXIOM>

Yes. The way to do this is to _avoid_ PIs as much as possible. PIs that are
required to interpret a document correctly are _inherently_
anti-portability, since the rule for PIs is that _any application_ should
be free to ignore them without changin the meaning of the document. The use
of SGML's PI syntax in XML is a not a good model for the use of PIs in
general, since they are being used in XML as a syntactic "escape hatch" for
compatibility with SGML. It would not be necessary (or desirable) if XML
were not (to some very small extent) changing SGML facilitied (as with
specifying the character encoding of entitites in PIs, rather than an SGML

If XML had been able to add declarations to SGML, that would have been done
instead of using the PI syntax.

>  <AXIOM> There is a critical mass of readers of this list who feel the
>need to address the problem.  </AXIOM>

Without a problem statement I'm not sure how to judge this, but it may well
be true.

>  <AXIOM> Anyone can use any PIs they like in their documents for whatever
>purposes they like without breaking the spirit of XML.  </AXIOM>

This is assuredly incorrect. PIs are intended for use in the case where a
practical _use_ of a document with _particular software_ requires
additional information that _should not_ have been indicated ina structural
description of the content. A paradigmatic example is the occasional need
to insert a page or column break in order to get acceptable formatting in a
particular processing situation (including: software, stylesheet, output
device). This is not information that _should_ be encoded in the abstract
representation of a document, but _may be essential_ for "getting the thing
to print right".

>  <AXIOM> That processing software need not (and so far won't) take any
>notice of these (or perhaps any) PIs
>  </AXIOM>

This is certainly essential. If you are saying something about you document
that you can imagine being useful to some software that you aren't using
right now -- then it should probably be in the markup. PIs are for things
that can be ignored without changing the interpretation of a document.

>  <AXIOM> If a few people find a way of doing something that works for
>them, and isn't against the spirit of the XML specs, then flaming their
>ideas is pointless.</AXIOM>

Even this is not necessarily true -- attacking the dissemination of false
or bad ideas is _never_ pointless, in that dissemination of bad information
(even if it serves a local porpose adequately well) can seriously mislead
people. For instance the use of styles in word-processing programs is
usually a very good idea. The fact that in some instances direct formatting
may work out, or even work better, should not stop people from quarreling
with public assertions about the utility of stylesheets based on those

To the extent that these axioms seem to be intended to rule out
disagreement of the merits of future proposals, I must take immediate and
strong exception to them. It's not possible for a responsible discussant
who disagrees with a public proposal of working practice to remain silent
on the topic. "Flaming" is usually not responsible discussion, but
principled disagreements should be expressed so that the issues are clear
to all.

><NOTE>The proposal I really want to address is, like Month Python's joke,
>so potentially dangerous that I dare not reveal it yet. The proposal here
>is also important to me - perhaps to others - and I hope servers as a
>useful example. It is NOT in a finalised form, but as can be seen from the
>meta-proposal, there is a method for referring to the a 'pseudo-final' form
>that is, at least, usable.

This makes me nervous

>That a PI of the form <?XDEV?> is 'reserved' by members of this list for
>PI-based proposals on this list. [We cannot use XML-DEV as 'XML' is rightly

We can certainly do this -- but as I said above, there are good reasons to
oppose the use of PIs for _any_ use that affects the semantics of

For example, even the proposed namespace PI would be vulnerable on this
account, except for the facts that:

   1. It's intended for use in _experiment_ with a proposed _extension_ of
XML. (In other words, the PI, should it be generally accepted for use with
all interested XML applications, would become part of XML).

   2. The prefix can be processed (and thus, the semantic information
accessed) _without_ software having to be aware of the namespace PI. In
other words, the PI can be treated as equivalent to a comment describing
the proposed intent of the tags that share a prefix. (In other words, you
can ignore the namespace PI, and still detect the semantic distinctions in
the document)

>That anyone can post a proposal to this list for the use of this PI.

Anyone can post anything anywhere.

>That any author can include an instance of such a proposed PI in their

Again, any author can put anything they want anywhere, good idea or not.

>That any writer of application software can write software to process such
>a PI.

Again, how could anyone stop them?

>That both of these should refer to an appropriate URL on this list's
>archive discussing outlining the use of this PI.

Certainly not a bad idea..

>That if someone doesn't approve of a proposal they ignore it rather than
>flaming it. The fittest ideas will survive.

In the long run this may (or for a number of reasons may not) be true.
However, bad ideas that are initially plausible but unworkable in the long
term (e.g., from a related, but different doamin, the creation and
management of large structured information cropora in raw HTML) would get
an artificial (and community-harmful) boost if an effective social
convention forbidding disagreement were in effect.

I agree that polite, reasoned disagreement is better than flaming
(impolite, ad-hominem disagreement) but in the intellectual world the unfit
perish faster under the lash of criticism.


David Durand              dgd at cs.bu.edu  \  david at dynamicDiagrams.com
Boston University Computer Science        \  Sr. Analyst
http://www.cs.bu.edu/students/grads/dgd/   \  Dynamic Diagrams
--------------------------------------------\  http://www.dynamicDiagrams.com/
MAPA: mapping for the WWW                    \__________________________

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