Node Collections in NamedNodeMaps and NodeLists
You can retrieve a set of nodes and put it in an ordered or unordered collection. When putting a set of nodes into an unordered collection, the set is called a NamedNodeMap by the World Wide Web Consortium (W3C); you can retrieve the data by name or index in this type of collection. Putting a set of nodes in an ordered collection is called a NodeList by the W3C, and the data can be retrieved by a zero-based index. NamedNodeMaps and NodeLists are described by the W3C. The implementations in the Microsoft .NET Framework for the NamedNodeMap is the XmlNamedNodeMap, and the NodeList is implemented by the XmlNodeList.
ConceptsXML Document Object Model (DOM)