The format string for the HTML code for the table heading row looks like:

<tr><th style="width:50%%">%s</th><th style="width:50%%">%s</tr>

Should there be a closing </th> before the closing </tr>? —[ AlanM1( talk)]— 23:10, 11 August 2013 (UTC) reply

fixed, thank you for finding the bug. Frietjes ( talk) 17:55, 12 August 2013 (UTC) reply

It would be nice to be able to insert a column in front of the two template result columns (i.e. a row header, |_rowheader=), the result being:

It would be nice to specify the optional table |_class=, too, and the header for that first column (|_header0=). Caption and header rows should not appear if not specified. I realize I might be asking to cram more into this template than it's intended for, too. Like maybe something more suited to a {{ Testcase table top}}, {{ Testcase table row}}, {{ Testcase table bottom}} trio. —[ AlanM1( talk)]—

@ AlanM1: added these features. should the rowheader be in a <th>...</th>? Frietjes ( talk) 18:07, 12 August 2013 (UTC) reply

@ Frietjes: thanks! Let's see. This is the wikicode used to mark header rows (from Help:Table):

{| class="wikitable"
|+ Multiplication table
|-
! scope="col" | ×
! scope="col" | 1
! scope="col" | 2
! scope="col" | 3
|-
! scope="row" | 1
| 1 || 2 || 3
|-
! scope="row" | 2
| 2 || 4 || 6
|-
! scope="row" | 3
| 3 || 6 || 9
|-
! scope="row" | 4
| 4 || 8 || 12
|-
! scope="row" | 5
| 5 || 10 || 15
|}

The resulting HTML looks like:

<table class="wikitable">
<caption>Multiplication table</caption>
<tr>
<th scope="col">×</th>
<th scope="col">1</th>
<th scope="col">2</th>
<th scope="col">3</th>
</tr>
<tr>
<th scope="row">1</th>
<td>1</td>
<td>2</td>
<td>3</td>
</tr>
<tr>
<th scope="row">2</th>
<td>2</td>
<td>4</td>
<td>6</td>
</tr>
...
</table>

so, yes, it seems you need <th scope="row">{{{_rowheader}}}</th> in HTML or ! scope="row" | {{{_rowheader}}} in WikiML. — Preceding unsigned comment added by 97.93.136.214 ( talk) 17:19, 13 August 2013 (UTC) reply