Namespaces

You have reached the URL associated with a namespace that is used in the examples of training courses and books by Priscilla Walmsley.

The main purpose of a namespace is not to point to a location where a resource resides. Instead, it is intended to provide a unique name that can be associated with a particular person or organization, much like Java package names. Therefore, namespace names are not required to be dereferencable. That is, there does not necessarily need to be an HTML page or other resource that can be accessed at this URL. The namespace name could point to a schema, an HTML page, a directory of resources, or nothing at all.

From here, you can get more information on Datypic's services or Priscilla Walmsley's books.