- From: Henry S. Thompson <ht@cogsci.ed.ac.uk>
- Date: 10 Jan 2001 09:03:06 +0000
- To: "Mark Young" <mark@kamiak.com>
- Cc: <xmlschema-dev@w3.org>
"Mark Young" <mark@kamiak.com> writes: > In section 4.3.3 of "XML Schema Part 1..." restriction has > simpleType as one of its allowed content items, while extension does > not (this under complexType / simpleContent). This seems > inconsistent; why is it allowed for restriction but not for > extension? You can never extend a simpleType with another simpleType -- this would mean some kind of concatenation, I guess, and we've never chosen to support this. This is true for both ordinary simple types, and complex types with simple content. What had you thought e.g. <xs:complexType> <xs:simpleContent> <xs:extension base="xs:string"> <xs:simpleType> <xs:restriction base="xs:integer"/> </xs:simpleType> </xs:extension> </xs:simpleContent> <xs:complexType> would mean? > Also, I don't believe that the normative schema schema has this for > complexType/simpleContent/restriction (i.e. no simpleType in the > content). Here is the type definition for <extension> when it appears inside <simpleContent>: <complexType name="simpleExtensionType"> <complexContent> <restriction base="extensionType"> <sequence> <annotation> <documentation xml:lang="en"> No typeDefParticle group reference</documentation> </annotation> <element ref="annotation" minOccurs="0"/> <group ref="attrDecls"/> </sequence> </restriction> </complexContent> </complexType> As you can see, it does _not_ allow <simpleType>, but only attribute declarations. ht -- Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh W3C Fellow 1999--2001, part-time member of W3C Team 2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440 Fax: (44) 131 650-4587, e-mail: ht@cogsci.ed.ac.uk URL: http://www.ltg.ed.ac.uk/~ht/
Received on Wednesday, 10 January 2001 04:03:13 UTC