I have a family of schemas for energy markets that are derived from a root abstract schema. In most cases, the derived types extend the abstract types by adding additional elements. This inheritance by addition is straight-forward. For one key abstract type, I use inheritance by restriction. Derived types must have all the elements of the root type, but they may be restricted to a few enumerated values. Consider the following, simplified and stripped down: Root Schema: <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="http://www.example.org/Base" targetNamespace="http://www.example.org/Base" elementFormDefault="qualified"> <xs:element name="A" type="AType"/> <xs:complexType name="AType" abstract="true"> <xs:sequence> <xs:element name="E1" type="xs:string"/> <xs:element name="E2" type="xs:string" /> </xs:sequence> </xs:complexType> Derivative schema <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns="http://www.example.org/Restriction" xmlns:base="http://www.example.org/Base" targetNamespace="http://www.example.org/Restriction" elementFormDefault="qualified"> <xs:import namespace="http://www.example.org/Base" schemaLocation="Base.xsd"/> <xs:element name="ARestricted" type="ARestrictedType"/> <xs:complexType name="ARestrictedType" abstract="false"> <xs:complexContent> <xs:restriction base="base:AType"> <xs:sequence> <xs:element name="E1" type="xs:string" fixed="foo"/> <xs:element name="E2"> <xs:simpleType> <xs:restriction base="xs:token"> <xs:enumeration value="fie"/> <xs:enumeration value="foe"/> </xs:restriction> </xs:simpleType> </xs:element> </xs:sequence> </xs:restriction> </xs:complexContent> </xs:complexType> The derivative schema is invalid. In particular, when processed, each element in ARestricted generates the following error: "rcase-NameAndTypeOK.1: The declarations' {name}s and {target namespace}s are not the same: restriction element is <xs:element name="itemDescription"> and base element is <xs:element name="itemDescription">." http://www.w3.org/TR/2004/REC-xmlschema-1-20041028/#rcase-NameAndTypeOK I can avoid the error if I change each of the schemas from elementFormDefault="qualified" to elementFormDefault="unqualified". The derived schema now validates using XML Spy and Liquid XML Studio. When I use the Liquid Technologies code generation tool to create software objects, the objects generate XML that looks like what I want. Here’s the question: Should I be looking for some side effect of switching these schemas from qualified to unqualified? Is there some hidden problem I will come upon if I require conforming schemas to be unqualified? I generally prefer “qualified” for the esthetic reason that I like to see explicit type derivations (prefices) in the schema. I do not have a feel for what else may be affected. Thanks tc "You can cut all the flowers but you cannot keep spring from coming."
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