code: function(name, url, params, options) {
          OpenLayers.Layer.KaMap.prototype.initialize.apply(this, arguments);
          this.extension = this.IMAGE_EXTENSIONS[this.params.i.toLowerCase() || this.DEFAULT_FORMAT];
      }
docs: Constructor: OpenLayers.Layer.KaMapCache
  
  Parameters:
  name - {String}
  url - {String}
  params - {Object} Parameters to be sent to the HTTP server in the
  query string for the tile. The format can be set via the 'i'
  parameter (defaults to jpg) , and the map should be set via
  the 'map' parameter. It has been reported that ka-Map may behave
  inconsistently if your format parameter does not match the format
  parameter configured in your config.php. (See ticket #327 for more
  information.)
  options - {Object} Additional options for the layer. Any of the
  APIProperties listed on this layer, and any layer types it
  extends, can be overridden through the options parameter.