protected function loadXmlFile( $fileName )
	{
		$root	= XML_ElementReader::readFile( $fileName );											//  get root element of XML file
		$this->pairs	= array();
		foreach( $root as $sectionNode )															//  iterate sections
		{
			$sectionName	= $sectionNode->getAttribute( 'name' );									//  get section name
			$this->loadXmlSection( $sectionNode, $sectionName );									//  read section
		}
		ksort( $this->pairs );																		//  sort resulting pairs by key
	}