xml-dev - Re: Associating DSSSL style sheets with documents

[Len Bullard <cbullard@hiwaay.net>]

Eve L. Maler wrote:
> 
> At 02:53 PM 3/14/97 -0600, Len Bullard wrote:
> >Eve L. Maler wrote:
> >>
> >>
> >> The difference is that, by convention, you're making PI markup available
> >> that's available to every document and to every *location* in a document if
> >> necessary, no matter what its DTD (and no matter whether it even has one).
> >> It just happens to look suspiciously like a start-tag, which may be helpful
> >> to any software that has to parse the PI string.
> >
> >By convention? You mean, by application.
> 
> I'm not sure I catch your distinction.  If we agree on a meaning and a
> syntax for it, we've made a convention.  

If we agree on a convention, one of us can break it at any time 
without a serious penalty.  If we make a contract, either can 
enforce it.  The PI is a contract.  So is the DTD we're 
trying to avoid with a hack.


> But XML doesn't have inclusions, and any one document may not even have
> DTDs.  So your "ifs" sometimes don't come true.  I agree that we don't want
> to push legitimate DTD functions into PIs, which give you a lot less
> validation power. But processing instructions (in the regular English
> sense) don't belong in the normal markup scheme most of the time.

Then why are they in the data?  Why were they deprecated?  What 
is in the SGML Way that is being overlooked here?  Why is it 
being overlooked?  Which is wrong:  the SGML Way or the use of PIs?

IOW, what the PIs you suggest do is put metainformation inside 
an instance.  Why?  What is it they will convey that an XML engine 
will not already know by reading the specification or could know 
by reading a DTD?  Is the DTD not there simply because members 
of the Working Group don't want them to be but now can't find 
a way to get around the functionality they provided?

> Well, a reference to a stylesheet is surely a link, but not all links are
> references to stylesheets.  Also, not all processing instructions are links
> to something.  Do you think PIs are never appropriate?

I didn't say that.  I'm wondering why they are suddenly a preferred 
practice when they were formerly a deprecated practice?  What is 
worse, a DTD I send once and might be very small, or PIs I send 
every time?

len

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