code: function(results, filename/*, options*/) {
              var messages = results.messages,
                  output = [];
  
              /**
               * Generate a source string for a rule.
               * Checkstyle source strings usually resemble Java class names e.g
               * net.csslint.SomeRuleName
               * @param {Object} rule
               * @return rule source as {String}
               */
              var generateSource = function(rule) {
                  if (!rule || !("name" in rule)) {
                      return "";
                  }
                  return "net.csslint." + rule.name.replace(/\s/g, "");
              };
  
  
              if (messages.length > 0) {
                  output.push("<file name=\""+filename+"\">");
                  CSSLint.Util.forEach(messages, function (message) {
                      // ignore rollups for now
                      if (!message.rollup) {
                          output.push("<error line=\"" + message.line + "\" column=\"" + message.col + "\" severity=\"" + message.type + "\"" +
                            " message=\"" + xmlEscape(message.message) + "\" source=\"" + generateSource(message.rule) +"\"/>");
                      }
                  });
                  output.push("</file>");
              }
  
              return output.join("");
          }
docs: Given CSS Lint results for a file, return output for this format.
  @param results {Object} with error and warning messages
  @param filename {String} relative file path
  @param options {Object} (UNUSED for now) specifies special handling of output
  @return {String} output for results