+ Example of using id and headers attributes. 

 <table summary="Column one has the location and size of accommodation, other columns show the type and number of properties available" border="1">
     <caption>
         Availability of holiday accommodation
     </caption>
     <thead>
         <tr>
             <td></td>
             <th id="stud" scope="col">
                 Studio
             </th>
             <th id="apt" scope="col">
                 <abbr title="Apartment">Apt</abbr>
             </th>
             <th id="chal" scope="col">
                 Chalet
             </th>
             <th id="villa" scope="col">
                 Villa
             </th>
         </tr>
     </thead>
     <tbody>
         <tr>
             <th id="par" class="span" colspan="5" scope="colgroup">
                 Paris
             </th>
         </tr>
         <tr>
             <th headers="par" id="pbed1">
                 1 bedroom
             </th>
             <td headers="par pbed1 stud">
                 11
             </td>
             <td headers="par pbed1 apt">
                 20
             </td>
             <td headers="par pbed1 chal">
                 25
             </td>
             <td headers="par pbed1 villa">
                 23
             </td>
         </tr>
         <tr>
             <th headers="par" id="pbed2">
                 2 bedroom
             </th>
             <td headers="par pbed2 stud">
                 -
             </td>
             <td headers="par pbed2 apt">
                 43
             </td>
             <td headers="par pbed2 chal">
                 52
             </td>
             <td headers="par pbed2 villa">
                 32
             </td>
         </tr>
         <tr>
             <th headers="par" id="pbed3">
                 3 bedroom
             </th>
             <td headers="par pbed3 stud">
                 -
             </td>
             <td headers="par pbed3 apt">
                 13
             </td>
             <td headers="par pbed3 chal">
                 15
             </td>
             <td headers="par pbed3 villa">
                 40
             </td>
         </tr>
         <tr>
             <th id="rome" class="span" colspan="5" scope="colgroup">
                 Rome
             </th>
         </tr>
         <tr>
             <th headers="rome" id="rbed1" headers="rome">
                 1 bedroom
             </th>
             <td headers="rome rbed1 stud">
                 13
             </td>
             <td headers="rome rbed1 apt">
                 21
             </td>
             <td headers="rome rbed1 chal">
                 22
             </td>
             <td headers="rome rbed1 villa">
                 3
             </td>
         </tr>
         <tr>
             <th headers="rome" id="rbed2" headers="rome">
                 2 bedroom
             </th>
             <td headers="rome rbed2 stud">
                 -
             </td>
             <td headers="rome rbed2 apt">
                 23
             </td>
             <td headers="rome rbed2 chal">
                 43
             </td>
             <td headers="rome rbed2 villa">
                 30
             </td>
         </tr>
         <tr>
             <th headers="rome" id="rbed3" headers="rome">
                 3 bedroom
             </th>
             <td headers="rome rbed3 stud">
                 -
             </td>
             <td headers="rome rbed3 apt">
                 16
             </td>
             <td headers="rome rbed3 chal">
                 32
             </td>
             <td headers="rome rbed3 villa">
                 40
             </td>
         </tr>
     </tbody>
 </table>