function Is () {
	// convert all characters to lowercase to simplify testing
    var agt=navigator.userAgent.toLowerCase();

    this.win   = ( (agt.indexOf("win")!=-1) || (agt.indexOf("16bit")!=-1) );
    // NOTE: On Opera 3.0, the userAgent string includes "Windows 95/NT4" on all
    // Win32, so you can't distinguish between Win95 and WinNT.
    this.win95 = ((agt.indexOf("win95")!=-1) || (agt.indexOf("windows 95")!=-1));

    // is this a 16 bit compiled version?
    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));

    // NOTE: Reliable detection of Win98 may not be possible. It appears that:
    // - On Nav 4.x and before you'll get plain "Windows" in userAgent.
    // - On Mercury client, the 32-bit version will return "Win98", but
    // the 16-bit version running on Win98 will still return "Win95".
    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.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));
}

 is = new Is();


 var isDOM      = (typeof(document.getElementsByTagName) != 'undefined'
                      && typeof(document.createElement) != 'undefined')
                   ? 1 : 0;
 var isIE4      = (typeof(document.all) != 'undefined'
                      && parseInt(navigator.appVersion) >= 4
                      && typeof(window.opera) == 'undefined')
                   ? 1 : 0;
 var isNS4      = (typeof(document.layers) != 'undefined')
                   ? 1 : 0;
 var isCapable    = (isDOM || isIE4 || isNS4)
                   ? 1 : 0;
// Uggly fix for Konqueror 2.2 that is half DOM compliant
if (isCapable && typeof(navigator.userAgent) != 'undefined') {
        var browserName = ' ' + navigator.userAgent.toLowerCase();
        if (browserName.indexOf('konqueror') > 0) {
            isCapable = 0;
        }
} 
/*
   if (isDOM) {
    }
    else {
      if (isIE4) {
      }
      else {
		  // si es noexplorer (netscape) plataforma windows
		  if (is.win){ 
		  } else
		  // si es noexplorer (netscape) plataforma linux
		  if (is.linux){ 
		  } else
		  // si es noexplorer (netscape) plataforma mac
		  if (is.mac){ 
		  }
		  else {
		  }
    }
 */