code: function Ext_DeductFormat(&$Ext, $Search) {
  		if (strpos(',odt,ods,odg,odf,odp,odm,ott,ots,otg,otp,', ',' . $Ext . ',') !== false) return 'odf';
  		if (strpos(',docx,xlsx,xlsm,pptx,', ',' . $Ext . ',') !== false) return 'openxml';
  		if (!$Search) return false;
  		if ($this->FileExists('content.xml')) {
  			// OpenOffice documents
  			if ($this->FileExists('META-INF/manifest.xml')) {
  				$Ext = '?'; // not needed for processing OpenOffice documents
  				return 'odf';
  			}
  		} elseif ($this->FileExists('[Content_Types].xml')) {
  			// Ms Office documents
  			if ($this->FileExists('word/document.xml')) {
  				$Ext = 'docx';
  				return 'openxml';
  			} elseif ($this->FileExists('xl/workbook.xml')) {
  				$Ext = 'xlsx';
  				return 'openxml';
  			} elseif ($this->FileExists('ppt/presentation.xml')) {
  				$Ext = 'pptx';
  				return 'openxml';
  			}
  		}
  		return false;
  	}
docs: Return the type of document corresponding to the given extension.