UWA widgets use a unique namespace, intended at the widget tag. That namespace uses the URI http://www.netvibes.com/ns/. This URL does not contain a webpage nor a Netvibes public page, but should return to this very informational page.

As said in the XML Namespace specification: “The namespace name, to serve its intended purpose, SHOULD have the characteristics of uniqueness and persistence. It is not a goal that it be directly usable for retrieval of a schema (if any exists).”

Hence, there does not need to be a page at that URI for the namespace to be functional: there mere fact that the URI does exist, is unique and is persistent, suffices.