docs: function(root, options) {
          var version;
          // read
          if (root) {
              version = this.version;
              if(!version) {
                  version = root.getAttribute("version");
                  if(!version) {
                      version = this.defaultVersion;
                  }
              }
          } else { // write
              version = (options && options.version) || 
                  this.version || this.defaultVersion;
          }
          return version;
      }