code: function(name, url, params, options) {
          OpenLayers.Layer.HTTPRequest.prototype.initialize.apply(this, 
                                                                  arguments);
          this.grid = [];
          this._removeBackBuffer = OpenLayers.Function.bind(this.removeBackBuffer, this);
  
          this.initProperties();
  
          this.rowSign = this.tileOriginCorner.substr(0, 1) === "t" ? 1 : -1;
      }
docs: Constructor: OpenLayers.Layer.Grid
  Create a new grid layer
  
  Parameters:
  name - {String}
  url - {String}
  params - {Object}
  options - {Object} Hashtable of extra options to tag onto the layer