code: private String getParentWBS(String wbs)
     {
        String result;
        int index = wbs.lastIndexOf('.');
        if (index == -1)
        {
           result = null;
        }
        else
        {
           result = wbs.substring(0, index);
        }
        return result;
     }
docs: Extract the parent WBS from a WBS.
  
  @param wbs current WBS
  @return parent WBS