This library allows you to manipulate XML files. It includes support
for reading, modifying and writing XML and HTML files. There is DTDs
support: this includes parsing and validation even with complex DtDs,
either at parse time or later once the document has been modified. The
output can be a simple SAX stream or and in-memory DOM-like
representations. In this case one can use the built-in XPath and
XPointer implementation to select subnodes or ranges. A flexible
Input/Output mechanism is available, with existing HTTP and FTP modules
and combined to a URI library.