var agt = navigator.userAgent.toLowerCase () ;
var is_major = parseInt (navigator.appVersion) ;
var is_minor = parseFloat (navigator.appVersion) ;

var is_safari = (agt.indexOf ("safari") != -1) ;

var is_nav  = ((agt.indexOf ('mozilla') != -1) && (agt.indexOf ('spoofer') == -1) && (agt.indexOf ('compatible') == -1) && (agt.indexOf ('opera') == -1) && (agt.indexOf ('webtv') == -1) && (agt.indexOf ('hotjava') == -1) && (agt.indexOf ('safari') == -1)) ;

var is_nav2 = (is_nav && (is_major == 2)) ;
var is_nav3 = (is_nav && (is_major == 3)) ;
var is_nav4 = (is_nav && (is_major == 4)) ;
var is_nav4up = (is_nav && (is_major >= 4)) ;
var is_navonly = (is_nav && ((agt.indexOf (";nav") != -1) || (agt.indexOf ("; nav") != -1))) ;
var is_nav6 = (is_nav && (is_major == 5) && (agt.indexOf("netscape") != -1) && (agt.indexOf ("netscape/7") == -1));
var is_nav6up = ((is_nav && (is_major >= 5)) || (is_nav && (agt.indexOf ('netscape/7') != -1))) ;
var is_gecko = (agt.indexOf ('gecko') != -1) ;

var is_ie     = ((agt.indexOf ("msie") != -1) && (agt.indexOf ("opera") == -1) && (agt.indexOf ("safari") == -1)) ;
var is_ie3    = (is_ie && (is_major < 4)) ;
var is_ie4    = (is_ie && (is_major == 4) && (agt.indexOf ("msie 4")!=-1) ) ;
var is_ie4up  = (is_ie && (is_major >= 4)) ;
var is_ie5    = (is_ie && (is_major == 4) && (agt.indexOf ("msie 5.0") != -1) ) ;
var is_ie5_5  = (is_ie && (is_major == 4) && (agt.indexOf ("msie 5.5") != -1)) ;
var is_ie5up  = (is_ie && !is_ie3 && !is_ie4) ;
var is_ie5_5up =(is_ie && !is_ie3 && !is_ie4 && !is_ie5) ;
var is_ie6    = (is_ie && (is_major == 4) && (agt.indexOf ("msie 6.") != -1)) ;
var is_ie6up  = (is_ie && !is_ie3 && !is_ie4 && !is_ie5 && !is_ie5_5 && !is_safari) ;
var is_ieMac = ((agt.indexOf ("msie") != -1) && (agt.indexOf ("mac_") != -1)) ;

var is_opera = (agt.indexOf ("opera") != -1) ;
var is_opera2 = (agt.indexOf ("opera 2") != -1 || agt.indexOf ("opera/2") != -1) ;
var is_opera3 = (agt.indexOf ("opera 3") != -1 || agt.indexOf("opera/3") != -1) ;
var is_opera4 = (agt.indexOf ("opera 4") != -1 || agt.indexOf("opera/4") != -1) ;
var is_opera5 = (agt.indexOf ("opera 5") != -1 || agt.indexOf("opera/5") != -1) ;
var is_opera5up = (is_opera && !is_opera2 && !is_opera3 && !is_opera4 && !is_opera5) ;
var is_opera7 = ((agt.indexOf ("opera/7.") != -1) || (agt.indexOf ("opera 7.") != -1)) ;