var _agent = navigator.userAgent.toLowerCase();

var _win = (_agent.indexOf('win') != -1);
var _mac = (_agent.indexOf('mac') != -1);

var _major = parseInt(navigator.appVersion);
var _minor = parseFloat(navigator.appVersion);

var _ns = ((_agent.indexOf('mozilla') != -1) && (_agent.indexOf('compatible') == -1));
var _ns2 = (_ns && (_major == 2));
var _ns3 = (_ns && (_major == 3));
var _nav = (_ns && ((_agent.indexOf(';nav') != -1) || (_agent.indexOf('; nav') != -1)));
var _nav3 = (_ns && _nav && (_major == 3));
var _nav4 = (_ns && _nav && (_major == 4));
var _ns4 = (_ns && (_major == 4));
var _ns4up = (_ns && (_major >= 4));
var _ns6 = (_ns && (_major == 5));
var _ns6up = (_ns && (_major >= 5));
var _ns61 = (_ns6 && (_agent.indexOf('netscape6/6.1') != -1));
var _ns62 = (_ns6 && (_agent.indexOf('netscape6/6.2') != -1));

/* mozilla */
var _moz = (_ns6 && (_agent.indexOf('netscape') == -1));

/* internet explorer */
var _ie = (_agent.indexOf('msie') != -1);
var _ie3 = (_ie && (_major < 4));
var _ie4 = (_ie && (_major == 4) && (_agent.indexOf('msie 5') == -1));
var _ie4up = (_ie && (_major >= 4));
var _ie45 = (_ie && (_minor == 4.5));
var _ie5 = (_ie && (_major == 4) && (_agent.indexOf('msie 5') != -1));
var _ie5up = (_ie && !_ie3 && !_ie4);
var _ie6 = (_ie && (_major == 4) && (_agent.indexOf('msie 6') != -1));

/* america online */
var _aol = (_agent.indexOf('aol') != -1);
var _aol3 = (_aol && _ie3);
var _aol4 = (_aol && _ie4);

/* opre */
var _opera = (_agent.indexOf('opera') != -1);
var _opera5 = (_opera && (_major == 5));
var _opera6 = (_opera && (_major == 6));

/* iCab (mac only) */
var _icab = (_agent.indexOf('icab') != -1);

/* web tv */
var _webtv = (_agent.indexOf('webtv') != -1);

/* omniweb */
var _omniweb = (_agent.indexOf('omniweb') != -1);