Libxml main interfaces
  - The parser: does Well-Formeness and DTD validation, handle namespaces,
    can operate in pull or push modes
 
  - SAX: callback based interface (opening, closing, characters ...)
 
  - DOM tree: build a full in-memory tree followingly DOM interfaces
 
  - HTML: an HTML parser, generating either SAX callbacks or a DOM tree
 
  - Tree: routines to create/modify/save a DOM tree. Being able to save back
    parsed documents influenced a lot of the design of libxml
 
  - URI module
 
  - I/0 interface: modular with basic FTP and HTTP built-in
 
  - I18N handlers: defaults UTF8 UTF16 and ISO-Latin, uses iconv if
  found
 
  - XPath expression language to query XML documents
 
  - Debug module (including a small shell) and memory usage checking