2244 2005-09-14 19:43:20 +0000 R-252: Final/block, transitivity and restriction 2009-04-21 19:21:39 +0000 1 1 1 Unclassified XML Schema Structures: XSD Part 1 unspecified All All CLOSED WONTFIX medium, hard, restriction cluster resolved P4 normal --- 1 sandygao cmsmcq www-xml-schema-comments oldest_to_newest 6274 0 sandygao 2005-09-14 19:43:20 +0000 In certain cases, I'm not sure the current REC makes the right call on when to do recursive checking up the base type chain and when not. Consider the following schema document: <xs:schema> <xs:element name="root" type="top"/> <xs:complexType name="top" final="restriction"> <xs:sequence> <xs:element name="a" minOccurs="0"/> </xs:sequence> </xs:complexType> <xs:complexType name="intermediate"> <xs:complexContent> <xs:extension base="top"> <xs:sequence> <xs:element name="b"/> </xs:sequence> </xs:extension> </xs:complexContent> </xs:complexType> <xs:complexType name="bottom"> <xs:complexContent> <xs:restriction base="intermediate"> <xs:sequence> <xs:element name="b"/> </xs:sequence> </xs:restriction> </xs:complexContent> </xs:complexType> <xs:complexType name="top2"> <xs:sequence> <xs:element name="c" type="top"/> </xs:sequence> </xs:complexType> <xs:complexType name="restrictOKorNot"> <xs:complexContent> <xs:restriction base="top2"> <xs:sequence> <xs:element name="c" type="bottom"/> </xs:sequence> </xs:restriction> </xs:complexContent> </xs:complexType> </xs:schema> The constraints on type definitions do _not_ recurse up the chain when checking 'final', so the type def named 'bottom' above is OK, despite restricting away an element ('a') introduced in a type definition which says it's final for restriction. However, content model checking _does_ recurse up the chain, so the type defn named 'restrictOKorNot' is _not_ OK. Neither is that following instance, wrt the schema corresponding to the above schema doc: <root xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:type="bottom"> <b/> </root> Is this really what we want? See http://lists.w3.org/Archives/Public/www-xml-schema-comments/2004JanMar/0087.html 13275 1 cmsmcq 2006-12-22 17:02:23 +0000 The WG agreed that the type RestrictOKorNot is not legal, and that it should not be. The chain of derivation from bottom to top has some non-restriction steps, and that means it should not be OK to substitute bottom for top in the restriction. The WG decided to make no change here. The originator of the comment, Henry Thompson, agrees.