Hi,
I have the following html table:

<table width="75%" border="1">
<tr>
<th rowspan="2">header1</th>
<th colspan="2">header2</th>
<th rowspan="2">header3</th>
<th rowspan="2">header4</th>
</tr>
<tr>
<th>header5</th>
<th>header6</th>
</tr>
<tr>
<th>row_header1</th>
<td>data1</td>
<td>data2</td>
<td>data3</td>
<td>data4</td>
</tr>
<tr>
<th>row_header2</th>
<td>data5</td>
<td>data6</td>
<td>data7</td>
<td>data8</td>
</tr>
<tr>
<th>row_header3</th>
<td>data9</td>
<td>data10</td>
<td>data11</td>
<td>data12</td>
</tr>
<tr>
<th>row_header4</th>
<td>data13</td>
<td>data14</td>
<td>data15</td>
<td>data16</td>
</tr>
</table>

to which I need to add the id attribute (I was able to do this with the position() function), and the headers attribute programmatically. The headers attribute has pointer values to the columns and rows headers of a cell:

<table width="75%" border="1">
<tr>
<th rowspan="2" id="un_0">header1</th>
<th colspan="2" id="un_1">header2</th>
<th rowspan="2" id="un_2">header3</th>
<th rowspan="2" id="un_3">header4</th>
</tr>
<tr>
<th id="un_4" headers="un_1">header5</th>
<th id="un_5" headers="un_1">header6</th>
</tr>
<tr>
<th id="un_6" headers="un_0">row_header1</th>
<td headers="un_1 un_4 un_6">data1</td>
<td headers="un_1 un_5 un_6">data2</td>
<td headers="un_2 un_6">data3</td>
<td headers="un_3 un_6">data4</td>
</tr>
<tr>
<th id="un_7" headers="un_0">row_header2</th>
<td headers="un_1 un_4 un_7">data5</td>
<td headers="un_1 un_5 un_7">data6</td>
<td headers="un_2 un_7">data7</td>
<td headers="un_3 un_7">data8</td>
</tr>
<tr>
<th id="un_8" headers="un_0">row_header3</th>
<td headers="un_1 un_4 un_8">data9</td>
<td headers="un_1 un_5 un_8">data10</td>
<td headers="un_2 un_8">data11</td>
<td headers="un_3 un_8">data12</td>
</tr>
<tr>
<th id="un_9" headers="un_0">row_header4</th>
<td headers="un_1 un_4 un_9">data13</td>
<td headers="un_1 un_5 un_9">data14</td>
<td headers="un_2 un_9">data15</td>
<td headers="un_3 un_9">data16</td>
</tr>
</table>

Do you have a suggestion on how I can write a stylesheet to do perform this. I have to use XSLT 1.0.
Thanks,
Francine.

I'm sorry, but I can't see the logic of why

<th id="un_4" headers="un_1">header5</th>
<th id="un_5" headers="un_1">header6</th>

point to un_1 rather than un_0. I'm afraid specification by example doesn't always work - the logic may be obvious to you, but it's not necessarily obvious to the reader. It would help to submit a much smaller example and explain the functional relationship more clearly.

Having said that, this kind of problem is hard in XSLT 1.0 (and it's no pleasure to solve it for someone who uses XSLT 2.0 every day). It's usually best to tackle it as a multi-pass transformation, with the first pass perhaps adding absolute row/column numbers of the top-left and bottom-right corners of each cell.

Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference

Michael,
There unfortunately is no standard logic for the table as the layout depends on the underlying data. In one case, header2 could be "Census Years" and header5 would be 2001 and header6 2006.
The reason why un_1 in
<th id="un_4" headers="un_1">header5</th>
<th id="un_5" headers="un_1">header6</th>
is because, the header cells span two rows except for header2 which spans two columns and is a pointer for header5 and header6. It would have been great to generate the pointers and ids dynamically using XSLT 1.0 (which the version handled by the built-in processor) but this might very complicated. So as you mention, this might have to be done using more than one transformation; I will use XSLT 2.0 to produce them statically.
Thanks for your suggestion,
Francine.