function is()
{	
	var agt=navigator.userAgent.toLowerCase();

    // *** BROWSER VERSION ***
    // Note: On IE5, these return 4, so use this.ie5up to detect IE5.
    this.major = parseInt(navigator.appVersion);
    this.minor = parseFloat(navigator.appVersion);

    // Note: Opera and WebTV spoof Navigator.  We do strict client detection.
    // If you want to allow spoofing, take out the tests for opera and webtv.
    this.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));
    this.nav2 = (this.nav && (this.major == 2));
    this.nav3 = (this.nav && (this.major == 3));
    this.nav4 = (this.nav && (this.major == 4));
    this.nav4up = (this.nav && (this.major >= 4));
    this.navonly      = (this.nav && ((agt.indexOf(";nav") != -1) ||
                          (agt.indexOf("; nav") != -1)) );
    this.nav6 = (this.nav && (this.major == 5));
    this.nav6up = (this.nav && (this.major >= 5));
    this.gecko = (agt.indexOf('gecko') != -1);
    this.ie     = ((agt.indexOf("msie") != -1) && (agt.indexOf("opera") == -1));
    this.ie3    = (this.ie && (this.major < 4));
    this.ie4    = (this.ie && (this.major == 4) && (agt.indexOf("msie 4")!=-1) );
    this.ie4up  = (this.ie && (this.major >= 4));
    this.ie5    = (this.ie && (this.major == 4) && (agt.indexOf("msie 5.0")!=-1) );
    this.ie5_5  = (this.ie && (this.major == 4) && (agt.indexOf("msie 5.5") !=-1));
    this.ie5up  = (this.ie && !this.ie3 && !this.ie4);
    this.ie5_5up =(this.ie && !this.ie3 && !this.ie4 && !this.ie5);
    this.ie6    = (this.ie && (this.major == 4) && (agt.indexOf("msie 6.")!=-1) );
    this.ie6up  = (this.ie && !this.ie3 && !this.ie4 && !this.ie5 && !this.ie5_5);

    // KNOWN BUG: On AOL4, returns false if IE3 is embedded browser
    // or if this is the first browser window opened.  Thus the
    // variables this.aol, this.aol3, and this.aol4 aren't 100% reliable.
    this.aol   = (agt.indexOf("aol") != -1);
    this.aol3  = (this.aol && this.ie3);
    this.aol4  = (this.aol && this.ie4);
    this.aol5  = (agt.indexOf("aol 5") != -1);
    this.aol6  = (agt.indexOf("aol 6") != -1);

    this.opera = (agt.indexOf("opera") != -1);
    this.opera2 = (agt.indexOf("opera 2") != -1 || agt.indexOf("opera/2") != -1);
    this.opera3 = (agt.indexOf("opera 3") != -1 || agt.indexOf("opera/3") != -1);
    this.opera4 = (agt.indexOf("opera 4") != -1 || agt.indexOf("opera/4") != -1);
    this.opera5 = (agt.indexOf("opera 5") != -1 || agt.indexOf("opera/5") != -1);
    this.opera5up = (this.opera && !this.opera2 && !this.opera3 && !this.opera4);

    this.webtv = (agt.indexOf("webtv") != -1); 

    this.TVNavigator = ((agt.indexOf("navio") != -1) || (agt.indexOf("navio_aoltv") != -1)); 
    this.AOLTV = this.TVNavigator;

    this.hotjava = (agt.indexOf("hotjava") != -1);
    this.hotjava3 = (this.hotjava && (this.major == 3));
    this.hotjava3up = (this.hotjava && (this.major >= 3));
    
    this.win   = (agt.indexOf("win")!=-1);
    this.mac   = (agt.indexOf("mac")!=-1);
    this.unix  = (agt.indexOf("x11")!=-1);
}    
var is=new is();