+
+ /**
+ * Array of axis index to { series : [ series names ] , options : { axis-specific options. }
+ * @type {Array.<{series : Array.<string>, options : Object}>} @private
+ */
+ this.yAxes_ = [];
+
+ /**
+ * Contains x-axis specific options, which are stored in the options key.
+ * This matches the yAxes_ object structure (by being a dictionary with an
+ * options element) allowing for shared code.
+ * @type {options: Object} @private
+ */
+ this.xAxis_ = {};