anchor.diff:             all_cells_of_this_epoch_column[i].remove();
            }
            
  -         
  +         deleteEpoch( epoch_index );
  +        
          }
          else
            return false;
            
           
       }
  -    
  -    function deleteEpochFromBackEnd( epoch_index )
  -    {
  -       createStudy.deleteEpoch( epoch_index , function(responseStr)
  -	   	{
  -             alert('deleted from backend : ' + responseStr);	   	
  -	   	});
  -    }
  -    
       
       function selectAll(event)
       {
  
positive.code:     
      function registerAddInstructionLinks()
      {
        var header_of_all_epochs = $$('.epoch');
         
        for(var i = 0 ; i < header_of_all_epochs.length ; i++ )
        {
          Event.observe('epochs['+i+'].descriptionText-id', 'click', addInstructions);   
        }
      }
      
      function unRegisterAddInstructionLinks()
      {
        var header_of_all_epochs = $$('.epoch');
         
        for(var i = 0 ; i < header_of_all_epochs.length ; i++ )
        {
          Event.stopObserving('epochs['+i+'].descriptionText-id', 'click', addInstructions);   
        }
      }
      
  
negative.code:       for(var i = 0 ; i < header_of_all_epochs.length ; i++ )
        {
          Event.observe('ck'+i, 'click', selectAll);
          
          var all_ck_boxes_for_this_column = $$('.ck'+i);
          for(var j = 0 ; j < all_ck_boxes_for_this_column.length ; j++ )
          {
            Event.observe(all_ck_boxes_for_this_column[j],'click', monitorCheckBoxes);
          } 
        }
      }
      
      function monitorCheckBoxes(event)
      {
        if( !$(Event.element(event).id).checked )
        {
          // if any check box is unselected, unselect appropriate selectAll checkBox
          var selectAllCkBoxID = Event.element(event).id.gsub(/(\w+)-(\d+)/,'#{1}'); 
          $(selectAllCkBoxID).checked = false;
        }
      }
      function unRegisterSelectAllCheckBoxes()
      {
        var header_of_all_epochs = $$('.epoch');
  