function Check(checkbox){
 checkbox.checked = true;
}

function Clear(checkbox){
 checkbox.checked = false;
}

function CheckAll(name){
 var ml = document.checklist;
 var len = ml.elements.length; 
 
 for (var i = 0; i < len; i++) {
  var checkbox = ml.elements[i];
  if (checkbox.name == name) {
   Check(checkbox);
  }
 }
}

function ClearAll(name){
 var ml = document.checklist;
 var len = ml.elements.length;
 for (var i = 0; i < len; i++) {
  var checkbox = ml.elements[i];
  if (checkbox.name == name) {
   Clear(checkbox);
  }
 }
}