RE: XSL FO DTD problems

Subject: RE: XSL FO DTD problems
From: Stephen Deach <sdeach@xxxxxxxxx>
Date: Fri, 25 Jun 1999 17:11:14 -0700
The DTD in the XSL (FO) spec is not actually a complete nor a valid DTD. We
used (SGML) DTD-syntax to describe 2 things:
  1.) The containment rules (How the tree is [may be] organized.)
  2.) Where properties were USED in the tree.

To be a proper DTD for validating the FO-Tree, it would be necessary to
change item 2 to be where properties may be supplied (specified) in the tree.

The person writing the DTD was familiar with features allows in SGML (that
are not allowed in XML and was more familiar with writing SGML DTDs), and
used those constructs (for example, exceptions) because it saved
significant repetition. In addition, several of the content models were
"simplified" and show that #PCDATA is allowed in an ordering that is not
supported in XML mixed-content models.

We do not believe it to be the case that the DTD 'could' not be made into a
valid XML DTD. Under deadline pressure, we simply didn't want to spent the
effort (in light of the fact that it was not intended to be used for
validation, but only to represent the 2 concepts described in the first
paragraph, above).

Do not try and read anything more into this.

   Editor WD-xsl-19990421

At 18:27 1999-06-25 -0400, you wrote:
>What is the significance of the fact that the XSL DTD cannot be expressed
>in... XML (syntax, semantics, whatever...)?
>	...edN
>> -----Original Message-----
>> From: owner-xsl-list@xxxxxxxxxxxxxxxx
>> [mailto:owner-xsl-list@xxxxxxxxxxxxxxxx]On Behalf Of Paul Grosso
>> Sent: Friday, June 25, 1999 5:06 PM
>> To: xsl-list@xxxxxxxxxxxxxxxx
>> Subject: Re: XSL FO DTD problems
>> At 13:49 1999 06 25 -0700, Rick Geimer wrote:
>> >Is it my imagination, or is the DTD for XSL formatting
>> objects (from the
>> >following URL) an invalid XML DTD?
>> >
>> >
>> >
>> >I tried parsing it with the XML parser in IE5, and IBM's
>> XML4C parser,
>> >and neither one accepted. However, it seems to be a valid SGML DTD.
>> You are right that it is an SGML DTD, not an XML DTD.  At this stage
>> (given that we don't yet have XML schemas and SGML DTD's are more
>> powerful that XML DTDs), this seemed to be the best way to express
>> what we needed to express.  This DTD is *not* meant to be used in
>> any specific way (e.g., in an implementation), it was merely the most
>> convenient expositional tool the editors had at their
>> immediate disposal.
>> >Does anyone know if there is a valid XML version of this DTD, or if
>> >there are plans to updated it for XML compliance?
>> It appears to me there are four logical choices:
>> 1.  leave it as an SGML DTD,
>> 2.  convert it to an XML DTD and lose useful information,
>> 3.  use something other than an XML or SGML DTD,
>> 4.  just delete the whole thing from the spec.
>> I don't know what the editors will decide to do.
>> (My preference is option 1, but I'm only one voice.)
>> paul
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  Stephen Deach                            |  Sr Computer Scientist
  408-536-6521 (office)                    |  Adobe Systems Inc.
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