Classes/Page/Part/MetatagPart.php
protected function isXhtml()
    {
        $ret = false;

        if (strpos($GLOBALS['TSFE']->config['config']['doctype'], 'xhtml') !== false) {
            // doctype xhtml
            $ret = true;
        }

        if (strpos($GLOBALS['TSFE']->config['config']['xhtmlDoctype'], 'xhtml') !== false) {
            // doctype xhtml doctype
            $ret = true;
        }

        return $ret;
    }
protected function isXhtml()
    {
        $ret = false;

        if (strpos($GLOBALS['TSFE']->config['config']['doctype'], 'xhtml') !== false) {
            // doctype xhtml
            $ret = true;
        }

        if (strpos($GLOBALS['TSFE']->config['config']['xhtmlDoctype'], 'xhtml') !== false) {
            // doctype xhtml doctype
            $ret = true;
        }

        return $ret;
    }
protected function isXhtml ( ) { $ ret = false ; if ( strpos ( $ GLOBALS [ 'TSFE' ] -> config [ 'config' ] [ 'doctype' ] , 'xhtml' ) !== false ) { // doctype xhtml $ ret = true ; } if ( strpos ( $ GLOBALS [ 'TSFE' ] -> config [ 'config' ] [ 'xhtmlDoctype' ] , 'xhtml' ) !== false ) { // doctype xhtml doctype $ ret = true ; } return $ ret ; }
Check if page is configured as XHTML

@return bool
Check if page is configured as XHTML