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As I mentioned previously, the seemingly contradictory dual nature of
the ur-type is a known issue in the spec which has been addressed.
More info at
http://lists.w3.org/Archives/Member/w3c-xml-schema-ig/2002Jan/0065.html
I assume an erratum will be published shortly.
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> -----Original Message-----
> From: Jeff Lowery [mailto:jlowery@scenicsoft.com]
> Sent: Friday, March 22, 2002 1:01 PM
> To: Jeff Lowery; Thomas B. Passin; xml-dev@lists.xml.org
> Subject: RE: [xml-dev] Who can implement W3C XML Schema ?
>
>
> Okay, I wrote my previous message at 3:30 am, but now I'm
> actually ready to think about this cute little issue.
>
> It's an interesting one, because (as it's been noted
> previously in this thread), the anyType is both simple and complex.
>
> If we treat the anyType as complex in the following:
>
> <element name="myElem">
> <complexType>
> <complexContent>
> <restriction base="anyType"/>
> </complexContent>
> </complexType>
> </element>
>
> we can come to the (correct) conclusion that since none of
> the (infinite) members of the anyType are mentioned, no
> element or attribute content is allowed for myElem. There's a
> related example in the Primer (2.5.3):
>
> <xsd:element name="internationalPrice">
> <xsd:complexType>
> <xsd:complexContent>
> <xsd:restriction base="xsd:anyType">
> <xsd:attribute name="currency" type="xsd:string"/>
> <xsd:attribute name="value" type="xsd:decimal"/>
> </xsd:restriction>
> </xsd:complexContent>
> </xsd:complexType>
> </xsd:element>
>
> which is equivalent to:
>
> <xsd:element name="internationalPrice">
> <xsd:complexType>
> <xsd:attribute name="currency" type="xsd:string"/>
> <xsd:attribute name="value" type="xsd:decimal"/>
> </xsd:complexType>
> </xsd:element>
>
>
> The internationalPrice element contains these two attributes,
> no child elements, and no data content. I remember checking
> the normative spec on this and the primer appears to be correct.
>
> But what is interesting is the simpleType nature of anyType.
> One could see an (incorrect) implemenation regarding the
> following to definitions as being
> equivalent:
>
> <elementname="myElem">
> <complexType>
> <complexContent>
> <restriction base="anyType"/>
> </complexContent>
> </complexType>
> </element>
>
>
> <element name="myElem" type="anySimpleType"/>
>
> And why not? The former definition merely restricts the
> children and attributes of a complex type by omitting them.
> But what of the data content? If you look at 2.2.1 of Part 1
> of the spec, you see:
>
> [Definition:] A distinguished ur-type definition is present
> in each *XML Schema*, serving as the root of the type
> definition hierarchy for that schema. The ur-type definition,
> whose name is anyType, has the unique characteristic that it
> can function as a complex or a simple type definition,
> according to context. Specifically, *restrictions* of the
> ur-type definition can themselves be either simple or complex
> type definitions.
>
> I still don't think that treating the two declarations above
> as equivalent is correct, but the following would be
> equivalent according to my
> understanding:
>
> <elementname="myElem" mixed="true">
> <complexType>
> <complexContent>
> <restriction base="anyType"/>
> </complexContent>
> </complexType>
> </element>
>
> <element name="myElem" type="anySimpleType"/>
>
>
> However, I'm traipsing into corner cases here, so I would
> gladly defer to those true spec mavens out there who spend a
> lot of time teasing things out of the spec. I aim squarely
> at the 80/20 point. Implementors of validating tools
> unfortunately don't have that luxury.
>
> Ciao,
>
> Jeff
>
>
> > -----Original Message-----
> > From: Jeff Lowery [mailto:jlowery@scenicsoft.com]
> > Sent: Friday, March 22, 2002 10:58 AM
> > To: Thomas B. Passin; xml-dev@lists.xml.org
> > Subject: RE: [xml-dev] Who can implement W3C XML Schema ?
> >
> >
> > Hey, why single me out? If Eric isn't sure, how likely am I to be?
> >
> > "According to my understanding" (and how it's written in _my_
> > book [watch
> > the elbows, Eric]), the element's content must be empty, since the
> > restriction reiterates nothing of the anyType. But somebody
> > pointed out an
> > errata somewhere so my interpretation may be suspect. But I
> > think it's what
> > the primer has, also. (I'd check, but my laptop's battery is
> > crapping out.)
> >
> > > Jeff Lowery, how about explaining this for us?
> > >
> > > Cheers,
> > >
> > > Tom P
> > >
> > >
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