function Is ()
{
    var agt=navigator.userAgent.toLowerCase()

    this.mjr=parseInt(navigator.appVersion)
    this.mnr=parseFloat(navigator.appVersion)

    this.nav=((agt.indexOf('mozilla')!=-1) && ((agt.indexOf('spoofer')==-1) && (agt.indexOf('compatible')==-1)))
    this.nav2=(this.nav && (this.mjr==2))
    this.nav3=(this.nav && (this.mjr==3))
    this.nav4=(this.nav && (this.mjr==4))
// remove following if fails and make nav4up
    this.nav5=(this.nav && (this.mjr==5))
    this.nav5up=this.nav && (this.mjr>=5)
    this.navonly   =(this.nav && (agt.indexOf(";nav")!=-1))

    this.ie=(agt.indexOf("msie") != -1)
    this.ie3=(this.ie && (this.mjr==2))
    this.ie4=(this.ie && (this.mjr==4))
    this.ie4up=this.ie && (this.mjr>=4)

    this.opera=(agt.indexOf("opera")!=-1)

    if (this.nav2 || this.ie3) this.js=1.0
    else if (this.nav3 || this.opera) this.js=1.1
    else if (this.nav4 || this.ie4) this.js=1.2
    else if ((this.nav && (this.mnr > 4.05)) || (this.ie && (this.mjr>4))) 
         this.js=1.2
    else this.js=0.0
}

var is;
var isIE3Mac=false;
var isIE4upMac=false;

if ((navigator.appVersion.indexOf("Mac")!=-1) && (navigator.userAgent.indexOf("MSIE")!=-1) && (parseInt(navigator.appVersion)==3))
       isIE3Mac=true;
else if ((navigator.appVersion.indexOf("Mac")!=-1) && (navigator.userAgent.indexOf("MSIE")!=-1) && (parseInt(navigator.appVersion)>=4))
       isIE4upMac=true;
else
       is=new Is();