function Is() {
    var agent = navigator.userAgent.toLowerCase();
    this.major = parseInt(navigator.appVersion);
    this.minor = parseFloat(navigator.appVersion);
    this.ns  = ((agent.indexOf('mozilla')!=-1) && ((agent.indexOf('spoofer')==-1) && (agent.indexOf('compatible') == -1)));
	this.ns3 = (this.ns && (this.major == 3));
    this.ns2 = (this.ns && (this.major == 2));
    this.ns4 = (this.ns && (this.major >= 4) && (this.major < 5) && (this.minor > 4.01));
	this.ns6 = (this.ns && (this.major >= 5));
    this.ie  = (agent.indexOf("msie") != -1);
	this.ie4up = (this.ie && !(this.major < 4));
    this.ie4  = (this.ie && (agent.indexOf("msie 4.")!=-1));
	this.ie5  = (this.ie && (agent.indexOf("msie 5.")!=-1));
	this.ie6  = (this.ie && (agent.indexOf("msie 6.")!=-1));
    this.win   = (agent.indexOf("win")!=-1);
    this.mac   = (agent.indexOf("mac")!=-1);
    this.unix  = (agent.indexOf("x11")!=-1);
	}

	is = new Is;