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Re: UPA and schema handling

• To: Joe English <jenglish@f...>
• Subject: Re: UPA and schema handling
• From: Bob Foster <bob@o...>
• Date: Fri, 22 Oct 2004 19:49:58 -0700
• Cc: xml-dev@l...
• In-reply-to: <200410222154.i9MLsFV09885@d...>
• References: <87lldyv5zk.fsf@n...> <41729D89.6020906@u...> <4172BD45.7040409@o...> <4172F10A.1070002@u...> <4173151B.90700@o...> <4173201E.20001@u...> <f5bu0smra97.fsf@e...> <41794B8B.9080709@m...> <200410222154.i9MLsFV09885@d...>
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Joe English wrote:
> But even SGML doesn't require conforming systems to report
> this condition; [4.267] says an ambiguous content model is not
> a "reportable markup error".
> 
> (That's probably because nobody knew *how* to detect this condition
> until 1992 when Anne Bruegemann-Klein figured it out, but still...)

Lots of people knew how to detect it, but they all did it differently. 
Bruegemann-Klein's great contribution was to provide a rigorous 
definition for the condition. (She then went on to show that if a 
grammar was deterministic by her definition, a DFA could be built for it 
in linear time. That was pretty nice, too.)

> Anyway, AIUI the consensus in the SGML world was that
> the prohibition against ambiguous content models was
> overly restrictive and unnecessary.  That W3C XML Schema
> retained the restriction was a big mistake, IMO, one
> that could easily have been avoided by not conflating
> validation with annotation.

You are so right. Look where it got us. XML Schema. Strongly typed XQuery.

Bob Foster

• Follow-Ups:
  • Re: UPA and schema handling
    • From: Burak Emir <Burak.Emir@e...>

• References:
  • Re: UPA and schema handling
    • From: Norman Walsh <ndw@n...>
  • UPA and schema handling
    • From: Ian Graham <ian.graham@u...>
  • Re: UPA and schema handling
    • From: Bob Foster <bob@o...>
  • Re: UPA and schema handling
    • From: Ian Graham <ian.graham@u...>
  • Re: UPA and schema handling
    • From: Bob Foster <bob@o...>
  • Re: UPA and schema handling
    • From: Ian Graham <ian.graham@u...>
  • Re: UPA and schema handling
    • From: ht@i... (Henry S. Thompson)
  • Re: UPA and schema handling
    • From: Elliotte Harold <elharo@m...>
  • Re: UPA and schema handling
    • From: Joe English <jenglish@f...>

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