docs: function SpriteSheetLoader(loadItem, preferXHR) {
  		this.AbstractLoader_constructor(loadItem, preferXHR, createjs.AbstractLoader.SPRITESHEET);
  
  		// protected properties
  		/**
  		 * An internal queue which loads the SpriteSheet's images.
  		 * @method _manifestQueue
  		 * @type {LoadQueue}
  		 * @private
  		 */
  		this._manifestQueue = null;
  	}