with header and footer information to comprise a well formed and valid xml including voicexml and all other xml derivatives sgml or html document this document can then be navigated and stored using cidnav most documents that are written by humans can be represented in a hierarchical u201c tree u201d structure a tree consists of u201c nodes u201d and has exactly one u201c top level u201d node nodes may contain an unlimited number of other nodes or u201c children u201d and a node that contains other nodes is known as a u201c parent u201d anode that does not contain any other nodes is known as a u201c leaf node u201d each child has an u201c index u201d within its parent and therefore there is the u201c first u201d child the u201c second u201d child if any and so on until the u201c last u201d child when representing a document as a tree the u201c top level node u201d is the document itself and each logical section of the document is contained as a child node each child node contains further divisions and child nodes and so on until each part of the document is represented as a node in the tree the leaf nodes of the tree contain the actual text of the document a good example of this structure is a common novel.