Table formatting challenge

Consider the following table:

+--------+--------+--------+--------+
|        |   B    |        |   D    |
+   A    +--------+   C    +--------+
|        |        |        |   E    |
+--------+--------+--------+--------+

Represented by this markup:

<informaltable>
<tgroup cols="4">
<colspec colname="c4" colnum="4"/>
<tbody>
<row>
  <entry morerows="1">A</entry>
  <entry>B</entry>
  <entry morerows="1">C</entry>
  <entry>D</entry>
</row>
<row>
  <entry namest="c4">E</entry>
</row>
</tbody>
</tgroup>
</informaltable>

The correct HTML for this table is:

<table border="1">
<tr>
  <td rowspan="2">A</td>
  <td>B</td>
  <td rowspan="2">C</td>
  <td>D</td>
</tr>
<tr>
  <td class="auto-generated"></td>
  <td>E</td>
</tr>
</table>

Can anyone see a practical way to achieve this result without
resorting to extension functions? The tricky bit is not simply
noticing that the introduction of namest may require some
auto-generated cells to be inserted, but calculating correctly, in the
presence of overhang (from an arbitrarily large number of preceeding
rows), how many cells to insert.

(This problem is slightly less serious in the FO case because
fo:table-cell elements have a column-number attribute; although there
are still some potential cell-border problems, I think.)

I'm hoping I've overlooked something clever and elegant.

                                        Be seeing you,
                                          norm

-- 
Norman.Walsh@xxxxxxx   | Our years, our debts, and our enemies are
XML Standards Engineer | always more numerous than we imagine.--Charles
Technology Dev. Group  | Nodier
Sun Microsystems, Inc. | 

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