The XMLSchema-instance Namespace

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The XMLSchema-instance Namespace

The XMLSchema-instance Namespace

The XMLSchema-instance namespace contains only four attributes. Here is a simplified version of the schema.

Code Sample:

Namespaces/Demos/XMLSchema-instance.xsd
<?xml version='1.0'?>
<xs:schema targetNamespace="http://www.w3.org/2001/XMLSchema-instance"
           xmlns:xs="http://www.w3.org/2001/XMLSchema">
   <xs:attribute name="nil"/>
 <xs:attribute name="type"/>
 <xs:attribute name="schemaLocation"/>
 <xs:attribute name="noNamespaceSchemaLocation"/>
</xs:schema>

By specifying that an XML document uses the XMLSchema-instance namespace, the instance author gets access to the four attributes declared above. We have already seen three of these attributes used.

  • xsi:nil is used to specify that an element has no value. It is covered in Nil Values.
  • xsi:schemaLocation is used to specify the location of a schema for a particular namespace.
  • xsi:noNamespaceSchemaLocation is used to specify the location of a schema when no namespace is used.
  • xsi:type is infrequently used to specify that the element in the instance is of a different type than the one declared in the schema for that element.
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