var agent = navigator.userAgent.toLowerCase();
var major = parseInt(navigator.appVersion);
var minor = parseFloat(navigator.appVersion);
var ns    = ((agent.indexOf('mozilla') != -1) && ((agent.indexOf('spoofer') == -1) && (agent.indexOf('compatible') == -1)));
var ns2   = (ns && (major == 3));
var ns3   = (ns && (major == 3));
var ns4b  = (ns && (major == 4) && (minor <= 4.03));
var ns4   = (ns && (major >= 4) && (major < 5));
var ns6   = (ns && (major >= 5));
var ie    = ((agent.indexOf("msie") != -1));
var ie3   = (ie && (major <  4));
var ie4   = (ie && (major >= 4) && (agent.indexOf("msie 5.0") == -1));
var ie5   = (ie && (major >= 4) && (agent.indexOf("msie 5.0") != -1));
var ie55  = (ie && (major >= 4) && (agent.indexOf("msie 5.5") != -1));
var opera = (agent.indexOf("opera") != -1);
var win   = (agent.indexOf("win")!=-1);
var mac   = (agent.indexOf("mac")!=-1);
var unix  = (agent.indexOf("x11")!=-1);