var app = navigator.appName.toLowerCase();
var ver = navigator.appVersion.toLowerCase();
// get the first character from the string.
ver = parseInt(ver.substring(0,1));

var ie3 = (app.indexOf("microsoft") != -1 && ver >= 4);
var nn3 = (app.indexOf("netscape") != -1 && ver >= 3);
var isRollover = (ie3 || nn3);
	
// Browser detection for IE3.0 or Netscape 3.0 or above
if (isRollover) {	
		btnpisOn = new Image;
		btnpisOn.src = "./images/product/btnpiso.gif";
		btnpisOff = new Image;
		btnpisOff.src = "./images/product/btnpis.gif";
		
		btnrocOn = new Image;
		btnrocOn.src = "./images/product/btnroco.gif";
		btnrocOff = new Image;
		btnrocOff.src = "./images/product/btnroc.gif";
	
		btndiaOn = new Image;
		btndiaOn.src = "./images/product/btndiao.gif";
		btndiaOff = new Image;
		btndiaOff.src = "./images/product/btndia.gif";

		btnrotOn = new Image;
		btnrotOn.src = "./images/product/btnroto.gif";
		btnrotOff = new Image;
		btnrotOff.src = "./images/product/btnrot.gif";

		btnregOn = new Image;
		btnregOn.src = "./images/product/btnrego.gif";
		btnregOff = new Image;
		btnregOff.src = "./images/product/btnreg.gif";

		btnairOn = new Image;
		btnairOn.src = "./images/product/btnairo.gif";
		btnairOff = new Image;
		btnairOff.src = "./images/product/btnair.gif";

		btnvacOn = new Image;
		btnvacOn.src = "./images/product/btnvaco.gif";
		btnvacOff = new Image;
		btnvacOff.src = "./images/product/btnvac.gif";

		btnsmaOn = new Image;
		btnsmaOn.src = "./images/product/btnsmao.gif";
		btnsmaOff = new Image;
		btnsmaOff.src = "./images/product/btnsma.gif";

}