function pad(number, length){
	var str = "" + number;
  while(str.length<length){
		str = '0' + str;
  }
  return str;
}

function addValueToHiddenField(field, value)
{
  var aids = new Array();
  var ids = field.value;
  if (ids.length > 0) {
    var aids = ids.split(',');
  }
  if (aids.indexOf(value) == -1) {
    aids.push(value);
  }
  field.value = aids.join(',');
}

function removeValueFromHiddenField(field, value)
{
  var ids = field.value;
  var aids = ids.split(','); // Safe assumption?
  var index = aids.indexOf(value);
  if (index != -1) {
    aids.splice(index, 1);
  }
  field.value = aids.join(',');
}