Associating a Schema With the Namespace of the Root Element
The namespace of the root element of an XML document can be associated with an XML Schema
using an XML catalog. If there is no
xsi:schemaLocation attribute on the root element and the XML document is
not matched with a document type, the
namespace of the root element is searched in the XML catalogs set in Preferences.
If the XML catalog contains a uri or rewriteUri or
delegateUri element, its schema will be used by the application to drive
the content completion and
document validation.