Inside XML

Schemas and Namespaces

One of the big ideas behind schemas was to allow XML processors to validate documents that use namespaces (which DTDs have a problem with). Toward that end, the <schema> element has a new attribute: targetNamespace.

The targetNamespace attribute specifies the namespace to which the schema is targeted—that is, the namespace that it is intended for. This means that if an XML processor is validating a document and is checking elements in a particular namespace, it will know what schema to check, based on the schema's target namespace. That's the idea behind target namespaces: You can indicate what namespace a schema is targeted to so that an XML processor can determine which schema(s) to use to validate a document.

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