protected function checkBrowserW3CValidator()
    {
        //Since the W3C validates pages with different robots we will prefix our versions with the part validated on the page...

        //W3C Link Checker (prefixed with "Link-")
        if ($this->checkSimpleBrowserUA('W3C-checklink', $this->_agent, self::BROWSER_W3CVALIDATOR, false, true)) {
            if ($this->getVersion() != self::VERSION_UNKNOWN) {
                $this->setVersion('Link-' . $this->getVersion());
            }
            return true;
        }

        //W3C CSS Validation Service (prefixed with "CSS-")
        if ($this->checkSimpleBrowserUA('Jigsaw', $this->_agent, self::BROWSER_W3CVALIDATOR, false, true)) {
            if ($this->getVersion() != self::VERSION_UNKNOWN) {
                $this->setVersion('CSS-' . $this->getVersion());
            }
            return true;
        }

        //W3C mobileOK Checker (prefixed with "mobileOK-")
        if ($this->checkSimpleBrowserUA('W3C-mobileOK', $this->_agent, self::BROWSER_W3CVALIDATOR, false, true)) {
            if ($this->getVersion() != self::VERSION_UNKNOWN) {
                $this->setVersion('mobileOK-' . $this->getVersion());
            }
            return true;
        }

        //W3C Markup Validation Service (no prefix)
        return $this->checkSimpleBrowserUA('W3C_Validator', $this->_agent, self::BROWSER_W3CVALIDATOR, false, true);
    }