var DOM = document.getElementById;
var Netscape4 = document.layer;
var Mozilla = (navigator.appName == "Netscape") && DOM;
var Netscape6 = (navigator.appName == "Netscape") && DOM;
var Netscape7 = navigator.userAgent.indexOf("Netscape/7") >= 0;
var Opera5 = window.opera && DOM;
var Opera6 = Opera5 && window.print;
var Opera7 = Opera5 && navigator.userAgent.indexOf("Opera 7") >= 0;
var IE = document.all && !Opera5;
var Firefox = navigator.userAgent.indexOf("Firefox") >= 0;

var Opera = Opera5|Opera6|Opera7;