Prefix is the namespace prefix of an element or attribute node's name. A namespace prefix is a symbolic name for a namespace URI. 

For element nodes, the namespace prefix is derived from the name that appears in the XML tag. For example, the namespace prefix for <xsi:Name First="John" Last="Doe"> is 'xsi'. 

For attribute nodes, the namespace prefix is derived from the string that appears to the left of the equals sign in the attribute declaration. For example the element <xsi:Name xsn:First="John" Last="Doe"> results in two attribute nodes, with namespace prefixes of 'xsn' and '', respectively. Note that the attribute never inherits a namespace prefix from the node to which it is attached. 

For any other node types, the namespace prefix is nil (Delphi) or NULL (C++). 

LocalName 

NodeType 

NamespaceURI