All XML handling based on libxml2
<?php
$dom 
= new domDocument;
$dom->load('menu.xml');
?>
presentations/slides/intro/menu.xml
XPath
<?php
$dom 
domdocument::load('menu.xml');
$ctx = new domXPath($dom);
$result $ctx->query('/breakfast_menu/food[@itemno > 3]/price/text()');
foreach(
$result as $node) {
  echo 
$node->nodeValue."<br />\n";
}
?>
Output