function Is() {   // convert all characters to lowercase to simplify testing
	var agt = navigator.userAgent.toLowerCase()

	// --- BROWSER VERSION ---
	this.major = parseInt(navigator.appVersion)
	this.minor = parseFloat(navigator.appVersion)

	this.nav  = ((agt.indexOf('mozilla') != -1) && ((agt.indexOf('spoofer') == -1) && (agt.indexOf('compatible') == -1)))
	this.nav2 = (this.nav && (this.major == 2))
	this.nav3 = (this.nav && (this.major == 3))
	this.nav4 = (this.nav && (this.major == 4))

	this.ie   = (agt.indexOf("msie") != -1)
	this.ie3  = (this.ie && (this.major == 2))
	this.ie4  = (this.ie && (this.major == 4))

	this.opera = (agt.indexOf("opera") != -1)
	 
	this.nav4up = this.nav && (this.major >= 4)
	this.ie4up  = this.ie  && (this.major >= 4)

	this.mac = (agt.indexOf("mac") != -1)
	
	this.safari = (agt.indexOf("safari") != -1);
	
	this.firefox = (agt.indexOf("navigator") == -1);

}

var is = new Is();