Interface for read only XML Namespace context processing.

An XML Namespace has the properties:

• Namespace URI: Namespace name expressed as a URI to which the prefix is bound
• prefix: syntactically, this is the part of the attribute name following the XMLConstants.XMLNS_ATTRIBUTE ("xmlns") in the Namespace declaration

example: <element xmlns:prefix="http://Namespace-name-URI">

All get*(*) methods operate in the current scope for Namespace URI and prefix resolution.

Note that a Namespace URI can be bound to multiple prefixes in the current scope. 

QName represents a qualified name as defined in the XML specifications: XML Schema Part2: Datatypes specification, Namespaces in XML, Namespaces in XML Errata.

The value of a QName contains a Namespace URI, local part and prefix.

The prefix is included in QName to retain lexical information when present in an XML input source .