W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > November 2001

datatypes: inheritence in schema RE: datatypes and MT

From: Jeremy Carroll <jjc@hplb.hpl.hp.com>
Date: Wed, 7 Nov 2001 10:02:52 -0000
To: <w3c-rdfcore-wg@w3.org>
Message-ID: <JAEBJCLMIFLKLOJGMELDOEGMCCAA.jjc@hplb.hpl.hp.com>
>
> The alternate is to impose the requirement that all lexical
> forms of all data types be valid lexical forms for all
> superordinate types of that data type. Ouch. Tough to
> verify...
>
> Granted, XML Schema seems to comply with such a requirement
> (I haven't checked rigorously though). But whether we
> could actualy empose such a requirement (either reasonably
> or practically) is questionable.
>



So, the simple types do appear to follow this.

The  derived types satisfy this by construction.

Derivation by restriction
http://www.w3.org/TR/xmlschema-2/#derivation-by-restriction
satisfies this by construction.


Derivation by list
http://www.w3.org/TR/xmlschema-2/#derivation-by-list
and by union
http://www.w3.org/TR/xmlschema-2/#derivation-by-union
satisfies this by virtue of not having a superclass (other than
anySimpleType)


The primitive datatypes inherit from anySimpleType, which appears by
definition to be a union of all the other types, and hence Patrick's
condition is satisfied.

The complex types (which have XML elements - see message later this morning)
seem more difficult, and I think in general Patrick's condition is false. I
am new to XML schema though, having only read part 2 last week, and parts 0
and 1 last night.

Jeremy
Received on Wednesday, 7 November 2001 05:03:11 EST

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