[XML-SIG] XML-SCHEMA

Christian Tismer tismer@trixie.triqs.com
Sun, 23 Apr 2000 23:05:21 +0200


Second reply to this, since I think something
more has to be said.

"Andrew M. Kuchling" wrote:
> 
> Andy Heath writes:
> >Are you guys doing anything about XML Schema?
> >
> >I know the spec is not out there in any final'ish form
> >yet but IMHO the whole world will go that way when it is.
> 
> I don't know if anyone is working on XML Schema support, but your
> message gave me the impetus to go to www.w3.org to take a look at the
> working drafts.
> 
> To my horror, the two parts of the XML schema WDs are 520K and 360K of
> HTML; that's huge!  (XML 1.0 is 188K.)  Didn't people want schemas
> because they thought DTD syntax was too complicated?

People want schemas since a DTD has limited expressiveness.
Schemas go far beyond DTDs. With schemas, you can express
new data types with constraints, you can build new abstract
types and assign rules about what they can contain.
You can explicitly describe what attributes and elements
may contain, by setting ranges, enumerating values and
giving regular expressions. New types can be built from
given/other types both by restriction and extension.
This all cannot be done with DTDs.

it-looks-like-I-will-have-to-support-this-ly y'rs -chris

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