function updateMeters(feetId, metersId) {
 
    var feet = document.getElementById(feetId);
    var meters = document.getElementById(metersId);
    
    if (feet == null)
      return;
    
    if (meters == null)
      return;
    
    meters.value = feet.value * 0.3048;
    meters.value = Math.round(meters.value);
  }

  function updateMetersSquare(feetId, metersId) {
 
    var feet = document.getElementById(feetId);
    var meters = document.getElementById(metersId);
    
    if (feet == null)
      return;
    
    if (meters == null)
      return;
    
    meters.value = feet.value * 0.092903;
    meters.value = Math.round(meters.value);
  }
  
  function updateFeet(feetId, metersId) {

    var feet = document.getElementById(feetId);
    var meters = document.getElementById(metersId);

    if (feet == null)
      return;
    
    if (meters == null)
      return;
    
    feet.value = meters.value / 0.3048;
    feet.value = Math.round(feet.value);
  }  

  function updateFeetSquare(feetId, metersId) {

    var feet = document.getElementById(feetId);
    var meters = document.getElementById(metersId);

    if (feet == null)
      return;
    
    if (meters == null)
      return;
    
    feet.value = meters.value / 0.092903;
    feet.value = Math.round(feet.value);
  }  

  function addSelectedItem(fromObjId, toObjId, toStorageObjTbId, toStorageObjId) {
  
   var fromObj = document.getElementById(fromObjId);
   var toObj = document.getElementById(toObjId);
   var toStorageTbObj = document.getElementById(toStorageObjTbId);
   var toStorageObj = document.getElementById(toStorageObjId);
   
   if (fromObj.selectedIndex >= 0) {
   
    var text = fromObj.options[fromObj.selectedIndex].text;
    var value = fromObj.options[fromObj.selectedIndex].value;       

    toObj.options[toObj.length] = new Option(text, value);
    
    fromObj.options[fromObj.selectedIndex] = null;
    
    toStorageTbObj.value = "";
    for (var i=0; i <= toStorageObj.length-1; i++) 
      toStorageTbObj.value += "," + toStorageObj.options[i].value;
   } 
  }
  
  function isDefined(variable) {
  
    return (typeof(window[variable]) == "undefined")?  false: true;
  }