anchor.diff:      var siblings = $A(thisArm.parentNode.getElementsByTagName("LI"))
   
       updateMoveControlVisibility('arm', thisArm.id.split('-')[1], thisArm, siblings)
  -    updateDeleteControlVisibility('arm', siblings);
   }
   
   function updateAllArmsControlVisibility(epochId) {
  -    var armItems = $$('#epoch-' + epochId + '-arms li');
  +    _updateAllArmsControlVisibility('epoch-' + epochId + '-arms')
  +}
  +
  +function _updateAllArmsControlVisibility(eltId) {
  +    var armItems = $$('#' + eltId + ' li');
       armItems.each(updateArmControlVisibility)
  +    updateDeleteControlVisibility('arm', armItems, eltId);
   }
   
   function createStudyControls() {
  
positive.code: <%@page contentType="text/javascript" %>
  <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
  function createAllArmControls() {
      $$('#epochs li.arm').each(createArmControls)
  }
  
  function createArmControls(armItem) {
  
negative.code:     var siblings = $$('div.epoch')
  
      updateMoveControlVisibility('epoch', thisEpoch.id.split('-')[1], thisEpoch, siblings)
      updateDeleteControlVisibility('epoch', siblings, 'epochs')
  }
  
  function updateAllEpochsControlVisibility() {
  