HTML验证错误：表格行开头没有单元格

Question

<table border="1">
  <tr>
    <td rowspan="4">A</td>
    <td colspan="5">B</td>
  </tr>
  <tr>
    <td colspan="3">E</td>
    <td rowspan="2">F</td>
    <td rowspan="4">C</td>
  </tr>
  <tr>
    <td rowspan="2">G</td>
    <td>
      <table border="1">
        <tr>
          <td>1</td><td>2</td>
        </tr>
        <tr>
          <td>3</td><td>4</td>
        </tr>
      </table>
    </td>
    <td>
      <table border="1">
        <tr>
          <td>1</td><td>2</td>
        </tr>
        <tr>
          <td>3</td><td>4</td>
        </tr>
      </table>
    </td>
  </tr>
  <tr>
    <td colspan="3">H</td>
  </tr>
  <tr>
    <td colspan="5">D</td>
  </tr>
</table>

W3C Validator complains, that: "Table column 6 established by element td has no cells beginning in it." even though cell 'C' should begin on 6th column. It displays correctly, so could it be a bug in the validator?

Answer 1

This appears to be a bug in the validator. It somehow fails to analyze the table properly.

Proving this might require a detailed analysis based on the HTML5 table model , but if you just add <col><col><col><col><col><col> right after the <table ...> tag, the markup passes validation – perhaps because it tells the browser that there are six columns and this helps the validator to recognize the status of the C cell properly. I accidentally noticed this when I added the col elements in order to set background colors on columns to visualize the situation better.

Consider posting a bug report and reporting back here if there will be progress there.