Apply the ContractNamespaceAttribute attribute to an assembly that contains types to which the DataContractAttribute has been applied. The ContractNamespaceAttribute enables you to set a namespace that is different than the one generated when the type is serialized. For more information about how names are generated, see Data Contract Names.
If you are using a type to conform to an existing data contract, you must match the namespace of the existing contract by using the ContractNamespaceAttribute (or the Namespace property of the DataContractAttribute class).
In any code, you can use the word ContractNamespace instead of the longer ContractNamespaceAttribute.