function ShowLayer ( whichLayer )
{
    turnOff( 'Students' );
    turnOff( 'Employers' );
    turnOff( 'Grad Students' );
    turnOff( 'Alumnus' );
    turnOff( 'Parents' );
    turnOff( 'Faculty' );
    turnOn( whichLayer );
}

function turnOn( whichLayer)
{
  var elem, vis;
  if( document.getElementById ) // this is the way the standards work
    elem = document.getElementById( whichLayer );
  else if( document.all ) // this is the way old msie versions work
      elem = document.all[whichLayer];
  else if( document.layers ) // this is the way nn4 works
    elem = document.layers[whichLayer];
  vis = elem.style;
  // if the style.display value is blank we try to figure it out here
  vis.display = 'block';
}

function turnOff( whichLayer)
{
  var elem, vis;
  if( document.getElementById ) // this is the way the standards work
    elem = document.getElementById( whichLayer );
  else if( document.all ) // this is the way old msie versions work
      elem = document.all[whichLayer];
  else if( document.layers ) // this is the way nn4 works
    elem = document.layers[whichLayer];
  vis = elem.style;
  // if the style.display value is blank we try to figure it out here
  vis.display = 'none';
}

function elementById(id)
{
  var elem;
  if( document.getElementById ) // this is the way the standards work
    elem = document.getElementById( id );
  else if( document.all ) // this is the way old msie versions work
      elem = document.all[id];
  else if( document.layers ) // this is the way nn4 works
    elem = document.layers[id];
    
 return elem;
}

window.location.querystring = (function() {
    var collection = {};
 
    // Gets the query string, starts with '?'
 
    var querystring = window.location.search;
 
    // Empty if no query string
 
    if (!querystring) {
        return { toString: function() { return ""; } };
    }
 
    // Decode query string and remove '?'
 
    querystring = decodeURI(querystring.substring(1));
 
   // Load the key/values of the return collection
 
    var pairs = querystring.split("&");
 
    for (var i = 0; i < pairs.length; i++) {
 
        // Empty pair (e.g. ?key=val&&key2=val2)
 
        if (!pairs[i]) {
            continue;
        }
 
        // Don't use split("=") in case value has "=" in it
 
        var seperatorPosition = pairs[i].indexOf("=");
 
        if (seperatorPosition == -1) {
            collection[pairs[i]] = "";
        }
        else {
            collection[pairs[i].substring(0, seperatorPosition)] 
                = pairs[i].substr(seperatorPosition + 1);
        }
    }
 
    // toString() returns the key/value pairs concatenated
 
    collection.toString = function() {
        return "?" + querystring;
    };
 
    return collection;
})();