Введение
  
   XML (eXtensible Markup Language) is a data format for structured
   document interchange on the Web.  It is a standard defined by
   The World Wide Web consortium (W3C).  Information about XML and
   related technologies can be found at » http://www.w3.org/XML/.
  
  
   This PHP extension implements support for James Clark's
   expat in PHP.  This toolkit lets you
   parse, but not validate, XML documents.  It supports three
   source character encodings
   also provided by PHP: US-ASCII,
   ISO-8859-1 and UTF-8.
   UTF-16 is not supported.
  
  
   This extension lets you create XML parsers
   and then define handlers for different XML
   events.  Each XML parser also has a few parameters you
   can adjust.