var av = navigator.appVersion;
var ua = navigator.userAgent;

var platform = new Object ();

platform.is_IE           = av.indexOf("MSIE")     > -1;      // (any version)
platform.is_IE7          = av.indexOf("MSIE 7.0") > -1;
platform.is_IE6          = av.indexOf("MSIE 6.0") > -1;
platform.is_IE50         = av.indexOf("MSIE 5.0") > -1;
platform.is_IE55         = av.indexOf("MSIE 5.5") > -1;
platform.is_IE55orHigher = av.indexOf("MSIE") > -1 && parseFloat(av.substr(av.indexOf("MSIE") + 4)) >= 5.5;

platform.is_Gecko        = ua.indexOf("Gecko")    > -1;      // (any Gecko-based browser including Mozilla, Beonix, AOL, Netscape 6.0+, etc.)
platform.is_Mozilla      = ua.indexOf("Mozilla")  > -1;      // (any version including Mozilla, Firefox, Firebird, Phoenix, Netscape)
platform.is_Firefox      = ua.indexOf("Firefox")  > -1;
platform.is_Firebird     = ua.indexOf("Firebird") > -1;
platform.is_Phoenix      = ua.indexOf("Phoenix")  > -1;
platform.is_Netscape     = ua.indexOf("Mozilla")  > -1;      // (vs. Mozilla?)

platform.is_OldNetscape  = ua.indexOf("Mozilla")  > -1 && parseFloat(av) < 5.0;   // Netscape 4.X or older