docs: function(name, url, params, options) {
          
          OpenLayers.Layer.Grid.prototype.initialize.apply(this, arguments);
          
          // unless explicitly set in options, if the layer is transparent, 
          // it will be an overlay
          if (options == null || options.isBaseLayer == null) {
              this.isBaseLayer = ((this.transparent != "true") && 
                                  (this.transparent != true));
          }
  
          if (options && options.useOverlay!=null) {
            this.useOverlay = options.useOverlay;
          }
          
          //initialize for untiled layers
          if (this.singleTile) {
            if (this.useOverlay) {
              OpenLayers.Util.applyDefaults(
                             this.params,
                             this.OVERLAY_PARAMS
                             );
              if (!this.useAsyncOverlay) {
                this.params.version = "1.0.0";
              }
            } else {
              OpenLayers.Util.applyDefaults(
                             this.params,
                             this.SINGLE_TILE_PARAMS
                             );
            }         
          } else {
              //initialize for tiled layers
              if (this.useHttpTile) {
                  OpenLayers.Util.applyDefaults(
                                 this.params,
                                 this.FOLDER_PARAMS
                                 );
              } else {
                  OpenLayers.Util.applyDefaults(
                                 this.params,
                                 this.TILE_PARAMS
                                 );
              }
              this.setTileSize(this.defaultSize); 
          }
      }