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Re: Accepting non-deterministic content models

• From: Lars Marius Garshol <larsga@g...>
• To: xml-dev@l...
• Date: Mon, 09 Jul 2001 11:47:24 +0200

* Lars Marius Garshol
|
| The only reason to reject non-deterministic content models is because
| the SGML standard requires it, and so for backwards compatibility XML
| did the same. This is also why the requirement is so vague. It doesn't
| say "should", it says "for compatibility, it is an error if...".

* John Cowan
| 
| [...] This was done so that existing SGML parsers could handle XML.
| I still often parse XML with nsgmls, for example.

I know. But since SGML had to be changed anyway, I think it should
also have been changed to allow non-deterministic content models in
"XML mode"; that is, when &-connectors are turned off in the SGML
declaration. 
 
* Lars Marius Garshol
|
| If this approach is followed, you have to do extra work to detect
| whether the original content model was "non-deterministic". In fact, 
| the reason why xmlproc accepts such content models (as Tom Passin
| reports) is that I haven't implemented this check yet. I don't think
| there's all that much point in doing so, either.
 
* John Cowan
|
| The language "it is an error" means that your processor need not
| detect it.  So if you don't want to add it, don't.

I know. I'm arguing on two levels at once here, and not keeping them
straight. XML being the way it is I think there _is_ a point in
implementing this. But I think there is absolutely no point in having
XML be this way.
 
* Lars Marius Garshol
|
| Now that we've ended up with a spec that is the way it is, I think the
| best course to follow for an implementation is to accept such content
| models, but to warn about them. 
 
* John Cowan
|
| That too is a reasonable course of action, since it protects
| the document author against non-portable documents.

That is the idea.

--Lars M.

• References:
  • Re: Accepting non-deterministic content models
    • From: John Cowan <cowan@m...>

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