XPath Prefix Mapping
To define default mappings between prefixes and namespace URIs go to the XPath preferences page and enter the mappings in the Default prefix-namespace mappings table. The same preferences panel allows you to configure the default namespace used in XPath 2.0 expressions.
Important:
If you define a default namespace, Oxygen XML Author Eclipse plugin binds this
namespace to the first free prefix from the list:
default,
default1, default2, and so on. For example, if you define
the default namespace xmlns="something" and the prefix
default is not associated with another namespace, you can match tags
without prefix in an XPath expression typed in the XPath toolbar by using the prefix
default. To find all the <level> elements when you
define a default namespace in the root element, use this expression:
//default:level in the XPath toolbar.