function Is() {
	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)
		&& (agent.indexOf('opera') == -1)
		&& (agent.indexOf('webtv') == -1)
		&& (agent.indexOf('hotjava') == -1));
		
	this.ns2 = (this.ns && (this.major == 2));
	
	this.ns3 = (this.ns && (this.major == 3));
	
	this.ns4 = (this.ns && (this.major == 4));
	
	this.ns6 = (this.ns && (this.major >= 5));
	
	this.ie = ((agent.indexOf('msie') != -1) 
		&& (agent.indexOf('opera') == -1));
		
	this.ie3 = (this.ie && (this.major < 4));
	
	this.ie4 = (this.ie && (this.major == 4) 
		&& (agent.indexOf("msie 4") != -1));
		
	this.ie5 = (this.ie && (this.major == 4) 
		&& (agent.indexOf("msie 5.") != -1)
		&& (agent.indexOf("msie 5.5") == -1) 
		&& (agent.indexOf("mac") == -1));
		
	this.iem5 = (this.ie && (this.major == 4) 
		&& (agent.indexOf("msie 5.") != -1) 
		&& (agent.indexOf("mac") != -1));
		
	this.ie55 = (this.ie && (this.major == 4) 
		&& (agent.indexOf("msie 5.5") != -1));
		
	this.ie6 = (this.ie && (this.major == 4) 
		&& (agent.indexOf("msie 6.") != -1));
		
	this.ie7 = (this.ie && (this.major == 4) 
		&& (agent.indexOf("msie 7.0b") != -1));
		
	this.nsdom = (this.ns4 || this.ns6);
	this.ie5dom = (this.ie5 || this.iem5 || this.ie55);
	this.iedom = (this.ie4 || this.ie5dom || this.ie6);
	this.w3dom = (this.ns6 || this.ie6 ||this.ie7);
}