code: function(options) {
          var layer = this.layer;
          layer.events.triggerEvent("loadstart", {filter: layer.filter});
          layer.protocol.read(OpenLayers.Util.applyDefaults({
              callback: this.merge,
              filter: layer.filter,
              scope: this
          }, options));
          layer.events.un({
              "visibilitychanged": this.load,
              scope: this
          });
      }
docs: Method: load
  Tells protocol to load data and unhooks the visibilitychanged event
  
  Parameters:
  options - {Object} options to pass to protocol read.