Comment out HTML and PHP together

Instead of using HTML comments (which have no effect on PHP code — which will still be executed), you should use PHP comments:

<?php /*
<tr>
      <td><?php echo $entry_keyword; ?></td>
      <td><input type="text" name="keyword" value="<?php echo $keyword; ?>" /></td>
    </tr>
    <tr>
      <td><?php echo $entry_sort_order; ?></td>
      <td><input name="sort_order" value="<?php echo $sort_order; ?>" size="1" /></td>
    </tr>
*/ ?>

With that, the PHP code inside the HTML will not be executed; and nothing (not the HTML, not the PHP, not the result of its non-execution) will be displayed.

Just one note: you cannot nest C-style comments… which means the comment will end at the first */ encountered.