function Is ()
{
    var agt=navigator.userAgent.toLowerCase();
    this.major = parseInt(navigator.appVersion);
    this.minor = parseFloat(navigator.appVersion);
    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);
    this.safari = (agt.indexOf('safari') != -1);
    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) || (agt.indexOf("16bit")!=-1) );
    this.win95 = ((agt.indexOf("win95")!=-1) || (agt.indexOf("windows 95")!=-1));
    this.win16 = ((agt.indexOf("win16")!=-1) || (agt.indexOf("16bit")!=-1) || (agt.indexOf("windows 3.1")!=-1) || (agt.indexOf("windows 16-bit")!=-1) );  
    this.win31 = ((agt.indexOf("windows 3.1")!=-1) || (agt.indexOf("win16")!=-1) || (agt.indexOf("windows 16-bit")!=-1));
    this.win98 = ((agt.indexOf("win98")!=-1) || (agt.indexOf("windows 98")!=-1));
    this.winnt = ((agt.indexOf("winnt")!=-1) || (agt.indexOf("windows nt")!=-1));
    this.win32 = (this.win95 || this.winnt || this.win98 || ((this.major >= 4) && (navigator.platform == "Win32")) || (agt.indexOf("win32")!=-1) || (agt.indexOf("32bit")!=-1));
    this.winme = ((agt.indexOf("win 9x 4.90")!=-1));
    this.win2k = ((agt.indexOf("windows nt 5.0")!=-1));
    this.os2   = ((agt.indexOf("os/2")!=-1) || (navigator.appVersion.indexOf("OS/2")!=-1) || (agt.indexOf("ibm-webexplorer")!=-1));
    this.mac    = (agt.indexOf("mac")!=-1);
    this.mac68k = (this.mac && ((agt.indexOf("68k")!=-1) || (agt.indexOf("68000")!=-1)));
    this.macppc = (this.mac && ((agt.indexOf("ppc")!=-1) || (agt.indexOf("powerpc")!=-1)));
    this.sun   = (agt.indexOf("sunos")!=-1);
    this.sun4  = (agt.indexOf("sunos 4")!=-1);
    this.sun5  = (agt.indexOf("sunos 5")!=-1);
    this.suni86= (this.sun && (agt.indexOf("i86")!=-1));
    this.irix  = (agt.indexOf("irix") !=-1);    // SGI
    this.irix5 = (agt.indexOf("irix 5") !=-1);
    this.irix6 = ((agt.indexOf("irix 6") !=-1) || (agt.indexOf("irix6") !=-1));
    this.hpux  = (agt.indexOf("hp-ux")!=-1);
    this.hpux9 = (this.hpux && (agt.indexOf("09.")!=-1));
    this.hpux10= (this.hpux && (agt.indexOf("10.")!=-1));
    this.aix   = (agt.indexOf("aix") !=-1);      // IBM
    this.aix1  = (agt.indexOf("aix 1") !=-1);    
    this.aix2  = (agt.indexOf("aix 2") !=-1);    
    this.aix3  = (agt.indexOf("aix 3") !=-1);    
    this.aix4  = (agt.indexOf("aix 4") !=-1);    
    this.linux = (agt.indexOf("inux")!=-1);
    this.sco   = (agt.indexOf("sco")!=-1) || (agt.indexOf("unix_sv")!=-1);
    this.unixware = (agt.indexOf("unix_system_v")!=-1); 
    this.mpras    = (agt.indexOf("ncr")!=-1); 
    this.reliant  = (agt.indexOf("reliantunix")!=-1);
    this.dec   = ((agt.indexOf("dec")!=-1) || (agt.indexOf("osf1")!=-1) || (agt.indexOf("dec_alpha")!=-1) || (agt.indexOf("alphaserver")!=-1) || (agt.indexOf("ultrix")!=-1) || (agt.indexOf("alphastation")!=-1)); 
    this.sinix = (agt.indexOf("sinix")!=-1);
    this.freebsd = (agt.indexOf("freebsd")!=-1);
    this.bsd = (agt.indexOf("bsd")!=-1);
    this.unix  = ((agt.indexOf("x11")!=-1) || this.sun || this.irix || this.hpux || this.sco ||this.unixware || this.mpras || this.reliant || this.dec || this.sinix || this.aix || this.linux || this.bsd || this.freebsd);
    this.vms   = ((agt.indexOf("vax")!=-1) || (agt.indexOf("openvms")!=-1));
}