var nn4 = false;	// Netscape Navigator or Communicator
var ie4 = false;
var ie5 = false;
var ie6 = false;
var moz = false;	// Mozilla, NS 6+, Konqueror, etc
var dom1 = false;	// fully supports DOM1
var dom2 = false;	// fully supports (important bits of) DOM2
var old = false;	// very old browser

function browser_detect() {
  // the official W3C way

  if ( window.document.implementation != null) {
    dom1 = window.document.implementation.hasFeature("HTML","1.0");
    dom2 = window.document.implementation.hasFeature("HTML","2.0") &&
    window.document.implementation.hasFeature("Events","2.0") &&
    window.document.implementation.hasFeature("Core","2.0") &&
    window.document.implementation.hasFeature("CSS2","2.0");
  }

  // Mozilla based browsers contain the Gecko rendering engine

  moz = (window.navigator != null )
        ? ( window.navigator.userAgent.indexOf("ecko") != -1 )
        : false;

  nn4 = (window.document.layers != null && !moz);

  // IE has incremental support for the Document Object Model

  ie6 = (window.document.all && dom1);
  ie5 = (window.document.all && window.document.getElementsByTagName && !ie6);
  ie4 = (window.document.all && !ie6 && !ie5);
   
  // something horrible and old - sorry Opera.

  old = (!ie5 && !ie6 && !dom2 && !moz);
}

browser_detect();