Table headers

Silktide checks that tables presenting data define header cells. Headers tell people using what each row and column means, something sighted readers infer from the table's layout.

Consider a table of surnames and cities. Without a header row, a value like "Washington" could be either - the meaning only becomes clear when the columns are labeled.

<!-- Problem: headings are ordinary cells, so they carry no meaning -->
<table>
  <tr>
    <td>Surname</td>
    <td>City</td>
  </tr>
  <tr>
    <td>Washington</td>
    <td>London</td>
  </tr>
</table>

Why this matters

A moves through a table one cell at a time. When headings are defined, it can announce the relevant heading alongside each value, so "London" is read as "City: London". Without headings, the listener hears a bare stream of values and has to memorize the table's layout to make sense of them - and for larger tables that is practically impossible.

Making the top row bold or a different colour is not enough. Visual styling carries no meaning for assistive technology; only the underlying does.

How to fix it

Change each heading cell from <td> to <th>, and add a scope attribute saying whether it heads a column or a row:

<!-- Fixed: headings are real header cells -->
<table>
  <tr>
    <th scope="col">Surname</th>
    <th scope="col">City</th>
  </tr>
  <tr>
    <td>Washington</td>
    <td>London</td>
  </tr>
</table>

If the table doesn't present data at all and is only used to arrange the page visually, add role="presentation" to the <table> element so assistive technology ignores its structure. Better still, replace layout tables with CSS - they are strongly discouraged in modern web design.

How Silktide tests this

Find every table on each page.
Skip tables marked as presentational with role="presentation".
Skip tables with only one row or only one column, which are unlikely to be data tables.
Report each remaining table that contains no <th> header cell at all.

Troubleshooting

My table has headings, but they are styled `<td>` cells

Cells that only look like headings do not count. Assistive technology cannot see fonts or colours; convert the cells to <th>.

My layout table is flagged

Silktide only skips layout tables that declare role="presentation". If a table is genuinely presentational, add that attribute - or replace the table with CSS layout.