function define_browser() {
	var browser_type = "";

	if (document.all)
		browser_type = "IE";				// IE & Opera (version >=7)
	else if ((navigator.userAgent.indexOf("Opera")!=-1) && (document.getElementById))
		browser_type = "OP";				// Opera (version <=6)
	else if (document.layers)
		browser_type = "NN"; 				// Netscape (version <=4)
	else 									// if (!document.all && document.getElementById)
		browser_type = "MO";				// Mozilla & FireFox & Netscape (version >=6)
	
	return browser_type;
}