function NativeLayer( config ) {

	// NativeLayer inherits from abstract layer "Layer"

	Layer.call( this, config );

	/**
	 * Hold handler for line group.
	 *
	 * @type { Object }
	 */

	this.lineGroupHandler = undefined;

	/**
	 * Identify whether layer is a merged layer or not.
     * If it's a NativeLayer, "isMerged" is always false.
	 *
	 * @type {boolean}
	 */

	this.isMerged = false;

}
addLineGroup() adds basic line group element to layer and holds the handler.