XML in a Nutshell, 3rd Edition

The Final Attribute

Until now, the schema has placed no restrictions on how other types or elements could be derived from its elements and types. The final attribute can be added to a complex type definition and set to either #all, extension, or restriction. On a simple type definition, it can be set to #all or to a list containing any combination of the values list, union, and/or restriction, in any order. When a type is derived from another type that has the final attribute set, the schema processor verifies that the desired derivation is legal. For example, a final attribute could prevent the physicalAddressType type from being extended:

<xs:complexType name="physicalAddressType" final="extension">

Since the main schema in address-schema.xsd attempts to redefine the physicalAddressType in an xs:redefine block, the schema processor generates the following errors when it attempts to validate the instance document:

ComplexType 'physicalAddressType': cos-ct-extends.1.1: Derivation by 
extension is forbidden by either the base type physicalAddressType_redefined 
or the schema.
Attribute "addr:latitude" must be declared for element type "physicalAddress".
Attribute "addr:longitude" must be declared for element type 
"physicalAddress".

The first error is a result of trying to extend a type that has been marked to prevent extension. The next two errors occur because the new, extended type was not parsed and applied to the content in the document. Now that you’ve seen how this works, removing ...