private void warnAboutAttribute(String name) throws SAXException {
        warn("The \u201C" + name + "\u201D attribute is not supported in"
                + " all browsers. Please be sure to test, and consider"
                + " using a polyfill.");
    }
@see nu.validator.checker.Checker#startElement(java.lang.String,
     java.lang.String, java.lang.String, org.xml.sax.Attributes)
src/nu/validator/checker/UnsupportedFeatureChecker.java