Rules:

1. Data tables must have proper table markup
2. Table headings must not be empty

Best practices

1. Provide captions to summarize the data table.

<table> 
	<tr>  
		<th>header 1</th>
		<th>header 2</th>
    <th>header 3</th>
	</tr>
	<tr>
		<td>cell 1</td>
		<td>cell 2</td>
		<td>cell 3</td>
  <tr>
</table>

<table>
	<tr>
		<th>Heading 1</th>
		<td>cell 1</td>
		<td>cell 2</td>
		<td>cell 3</td>
  <tr>
	<tr>
		<th>Heading 2</th>
		<td>cell 4</td>
		<td>cell 5</td>
		<td>cell 6</td>
  <tr>
	<tr>
		<th>Heading 3</th>
		<td>cell 7</td>
		<td>cell 8</td>
		<td>cell 9</td>
  <tr>
</table>

<table>
	<tr>
		<th>Heading 1</th>
		<th>Heading 2</th>
    <th>Heading 3</th>
	</tr>
	<tr>
		<td>cell 1</td>
		<td>cell 2</td>
		<td>cell 3</td>
  <tr>
</table>