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Re: Empty elements (and processing without a DTD)



At 02:37 PM 9/12/96 CDT, Michael Sperberg-McQueen wrote:
>It's also easily thinkable that XML processing tools could provide all
>the functionality that make Bob Streich want to keep marked sections.
>We might want to have marked sections in XML, I don't know.  But we
>don't *have* to have them, just because they currently provide essential
>function.  It's the function that's essential, not the construct of the
>marked section.  If we can find another way of providing that essential
>function, we don't need the marked section.  

Do people really need conditional markup? Or are they really interested in
conditionally _displayed_ markup. If the latter, style sheets could be used.
For instance, here's a graceful mechanism for migrating tables into an
HTML-like XML instance:

<TABLES.DEFINED><TABLE>...</TABLE></TABLES.DEFINED>
<NO.TABLES.DEFINED><PRE>...</PRE>

In a style sheet (in a bizarre syntax similar to my current programming
language), you could have something like:

TABLES.DEFINED(){
    if (!FEATURE_SUPPORTED(<TABLE>) )
       return NULL;
    else
        return process_children();
}

NO.TABLES.DEFINED(){
    if( FEATURE_SUPPORTED( <TABLE> ) )
        return NULL;
    else 
        return process_children();
}

Personally, I have never needed to use marked sections in instances for
anything other than conditional display. I do use them often in DTDs,
however. Maybe that's an argument against having DTDs be SGML instances.
Would "XML DTD-instances" themselves have a modifiable DTD that would allow
me to introduce these sorts of conditionals?

 Paul Prescod