code: function(options) {
    FunctionParameter.call(this, options);
  
    this.crs = defaultValue(options.crs, Reproject.TERRIA_CRS);
  }
docs: A parameter that specifies a bounding box/extent on the globe.
  
  @alias RectangleParameter
  @constructor
  @extends FunctionParameter
  
  @param {Object} options Object with the following properties:
  @param {Terria} options.terria The Terria instance.
  @param {String} options.id The unique ID of this parameter.
  @param {String} [options.name] The name of this parameter.  If not specified, the ID is used as the name.
  @param {String} [options.description] The description of the parameter.
  @param {Boolean} [options.defaultValue] The default value.
  @param {String} [options.crs] The Coordinate Reference System to use.