docs: function(moZoom) {
          var zoom = null;
          if (moZoom != null) {
              zoom = moZoom - this.minZoomLevel;
              if (this.map.baseLayer !== this) {
                  zoom = this.map.baseLayer.getZoomForResolution(
                      this.getResolutionForZoom(zoom)
                  );
              }
          }
          return zoom;
      }