anchor.diff:  
               <th>Start &amp; End Dates</th>
   
  -            <th>Duty rates</th>
  +            <th>Duty rates / Supplementary units</th>
   
               <th>Additional codes</th>
   
  
positive.code: 
              <th>Start &amp; End Dates</th>
  
              <th>Duty rates</th>
  
              <th>Additional codes</th>
  
  
negative.code: 
              <th scope="col">Start &amp; End Dates</th>
  
              <th scope="col">Duty rates / Supplementary units</th>
  
              <th scope="col">Additional codes</th>
  
  