Re: [xml-dev] a puzzling schema promise

[Liam R E Quin <liam@w3.org>]

On Tue, 2013-04-09 at 18:06 -0400, Simon St.Laurent wrote:
[...]
> --------------------------------------------------
> When XML is used to exchange technical information in a multi-vendor 
> environment, schemas will allow software to distinguish data governed by 
> industry-standard and vendor-specific schemas, and help applications 
> know when it is safe to ignore information they do not understand, and 
> when they must not do so.
> --------------------------------------------------
> 
> This sounds more... intricate than validation, but I'm guessing that's 
> all it really is.  Is there something more to "when it is safe to ignore 
> information they do not understand, and when they must not do so"?

I don't think that's one of mine, but...

In a Web services context there's the concept of "must-understand",
which I always felt to be a little silly in an XML context (where any
XML processor can process any XML document, regardless of
must-understand) but it does make sense in an application context.

With XSD it's also possible to mark elements as having less strict
validation applied to their content (e.g. lax).

Liam

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Liam Quin - XML Activity Lead, W3C, http://www.w3.org/People/Quin/
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