Fixed value only once in table

I want to produce a dynamic table which holds three columns. The first column
holds a fixed value (Extra) and should only occur on the first row. The second
and third column holds value from the xml-file and should be dynamic.

The xml file looks like

<choice_of_extra>
<code>711</code>
<specification>Cleaning</specification>
</choice_of_extra>
<choice_of_extra>
<code>511</code>
<specification>New towels</specification>
</choice_of_extra>

XSL

<table width="100%" border="0">
<tbody>
<xsl:for-each
select="tc:MESSAGE/tc:CUSTOM-ATT/b:empty_cart/b:choice_of_extra">
<tr>
<td width="10%">Extra</td>
<td width="10%"><xsl:value-of select="b:code"/></td>
<td width="80%"><xsl:value-of select="b:specification"/></td>
</tr>
</xsl:for-each>
</tbody>
</table>

Result

Extra  711  Cleaning
Extra  511  New towels

Wanted display

Extra  711  Cleaning
       511  New towels

Any ideas?

Regards

Mattias Pirmann