- From: Jeni Tennison <jeni@jenitennison.com>
- Date: Mon, 12 Nov 2001 17:12:14 +0000
- To: "K.Mroczek" <kmroczek@altkom.com.pl>
- CC: xmlschema-dev@w3.org
Hi Krzysztof, > What is the meaning (and syntax) of redefinitions <group> and > <attributeGroup>? Clauses 6.2 and 7.2 in "Schema Representation > Constraint: Redefinition Constraints and Semantics" (4.2.2 > structures) look like a method for redefinition by 'restriction'. > But what is the interpretation of clauses 6.1 and 7.1? Is it > describe a method for redefinition by 'extension'? Yes, 6.1 and 7.1 specify ways in which you can redefine groups and attributeGroups by adding new particles/attributes to them (extending them), and 6.2/7.2 are ways of redefining groups and attributeGroups by restricting them. For example if the base definition of group foo is: <xs:group name="foo"> <xs:sequence> <xs:element ref="A" minOccurs="0" /> <xs:element ref="B" minOccurs="0" /> </xs:sequence> </xs:group> Then you could have a restricting redefinition that restricted the sequence so that it *must* contain a B element with: <xs:redefine schemaLocation="..."> <xs:group name="foo"> <xs:sequence> <xs:element ref="B" /> </xs:sequence> </xs:group> </xs:redefine> And you could have an extending redefinition adding a C element with: <xs:redefine schemaLocation="..."> <xs:group name="foo"> <xs:sequence> <xs:group ref="foo" /> <xs:element ref="C" minOccurs="0" /> </xs:sequence> </xs:group> </xs:redefine> By my reading of the Rec the 'extension' of groups by redefinition are a lot less constrained than the extension of complex types. For example, you could equally have: <xs:redefine schemaLocation="..."> <xs:group name="foo"> <xs:sequence> <xs:element ref="C" minOccurs="0" /> <xs:group ref="foo" /> </xs:sequence> </xs:group> </xs:redefine> Or: <xs:redefine schemaLocation="..."> <xs:group name="foo"> <xs:choice> <xs:element ref="C" minOccurs="0" /> <xs:group ref="foo" /> </xs:choice> </xs:group> </xs:redefine> Cheers, Jeni --- Jeni Tennison http://www.jenitennison.com/
Received on Monday, 12 November 2001 12:12:24 UTC