code: function(newParams, altUrl) {
          var mapProjection = this.map.getProjectionObject();
          var projectionCode = this.projection && this.projection.equals(mapProjection) ?
              this.projection.getCode() :
              mapProjection.getCode();
          var value = (projectionCode == "none") ? null : projectionCode;
          if (parseFloat(this.params.VERSION) >= 1.3) {
              this.params.CRS = value;
          } else {
              this.params.SRS = value;
          }
          
          if (typeof this.params.TRANSPARENT == "boolean") {
              newParams.TRANSPARENT = this.params.TRANSPARENT ? "TRUE" : "FALSE";
          }
  
          return OpenLayers.Layer.Grid.prototype.getFullRequestString.apply(
                                                      this, arguments);
      }
docs: APIMethod: getFullRequestString
  Combine the layer's url with its params and these newParams.
  
  Add the SRS parameter from projection -- this is probably
  more eloquently done via a setProjection() method, but this
  works for now and always.
  
  Parameters:
  newParams - {Object}
  altUrl - {String} Use this as the url instead of the layer's url
  
  Returns:
  {String}