[rfc-i] DTD defaults for v3

Jim Schaad ietf at augustcellars.com
Tue Feb 18 11:40:10 PST 2014



> -----Original Message-----
> From: rfc-interest-bounces at rfc-editor.org
[mailto:rfc-interest-bounces at rfc-
> editor.org] On Behalf Of Paul Hoffman
> Sent: Saturday, February 15, 2014 3:10 PM
> To: Julian Reschke
> Cc: RFC Interest
> Subject: Re: [rfc-i] DTD defaults for v3
> 
> On Feb 15, 2014, at 12:31 PM, Julian Reschke <julian.reschke at gmx.de>
> wrote:
> 
> > On 2014-02-15 17:06, Paul Hoffman wrote:
> >> On Feb 15, 2014, at 6:24 AM, Julian Reschke <julian.reschke at gmx.de>
> wrote:
> >>
> >>> That's why DTD defaults are a bad thing; the infoset of the document
> varies depending on whether you use a validating parser or not.
> >>
> >> . . .
> >>
> >>>> Change the dtd so that the align attribute on artwork is implicit.
> >>>
> >>> That's a good change as well. We should do that consistently for all
> attributes.
> >>
> >> For the v3 document, I have been keeping the defaults from the v2
> document, and even adding in some new ones. Would it be better to
> remove them? Or am I misunderstanding your comments above?
> >
> > Defaults are bad when they are in a DTD, and the document is read by a
> validating XML parser (which seems to be the case for the v2 code).
> >
> > If we move away from DTDs the "defaulting" doesn't affect the parsing
> anymore, and thus would be purely for documentation.
> >
> > So we need to decide what our position with respect to DTDs is...
> 
> Yes, that's what this thread is about. :-) I suspect you have an opinion.
(I
> don't.)

Defaults are good for some things and bad for others.

I think that I disagree with Julian on the issue of inheritance of some
attributes (such as align for artwork).  I have no objections to the DTD
specifiying a default value in those cases where inheritance from a parent
makes no sense, but for things like list styles, alignment and so forth it
make more sense to have a default value that is enforced by the program than
by the dtd.

Jim

> 
> --Paul Hoffman
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