This mechanism would be used where new elements need to be added to the standard schema. An example might be a requirement to represent organisations through a new Organisation element. Under these circumstances, the author designing the extension needs to provide an associated XSD schema file defining the syntax of those new elements. The new XML elements and attributes are then referenced with the prefix of the associated namespace. For instance:
Text with embedded Organisation reference <org:OrgRef Key=’Org1’/>
A schema validation operation on such XML would use both the standard schema associated with the default unnamed namespace and the extended schema associated with the additional namespace.