Question

At the moment, HTML5 standards create titles/headings automatically from the first heading it finds in the article/section/nav etc. The problem I have is seeing why <caption> shouldn’t be treated the same way as headings (for the purpose of the outline).

Take the below code for example. It’s what you have to resort to in order to have a titled section in the document outline:

<table>
    <caption>Results from zombie duck experiment</caption>
    <h2 style="display: none;">Results from zombie duck experiment</h2>
    <tr>
        <td>FAILURE</td>
        <td>FAILURE</td>
    </tr>
</table>

(Which produces this outline: http://gsnedders.html5.org/outliner/process.py?url=http%3A%2F%2Froncya.com%2Ftransfer%2FHTML5CaptionDocumentOutline2.htm)

I understand why that works; HTMLDoctor go so far as to say that it is the recommended way of doing things:

For accessibility reasons, we recommend each sectioning element have a heading, even <aside> and <nav>. If you don’t want these headings to be visible, you can always hide them with CSS. —http://html5doctor.com/outlines/

Sure, but why not this?:

<table>
    <caption>Results from zombie duck experiment</caption>
    <tr>
        <td>FAILURE</td>
        <td>FAILURE</td>
    </tr>
</table>

(Which produces this failed outline: http://gsnedders.html5.org/outliner/process.py?url=http%3A%2F%2Froncya.com%2Ftransfer%2FHTML5CaptionDocumentOutline1.htm)

I’m assuming that the W3C made a conscious decision and the only ideas I have are that:

1. Tables, while they do have an ending tag, aren’t really used as ‘wrappers’ like div, span, article, section, nav and similar. So in that sense, they don’t define a ‘surrounded section’
2. Headings are headings and captions are not headings (…which doesn’t answer much)
3. Typical captions don’t make for suitable titles (I disagree with this)

As for number 3, I think that a typical caption would still be useful as a title in a document outline. Regardless of wether they’re on top of the table or below. Heck, I can’t even see why it would be worse than nothing. Take these possible captions for example- I reckon they would all be appropriate document outline section titles:

• Results from zombie duck experiment
• Figure 3b
• Windows 8 Region Pricing
• Which brand contains what?
• Cheat codes
• Colours
• Abraham Lincoln’s attire at different periods of history

It would sure make sense to me.

Answer 1

In HTML5, it’s intended that the caption contains not just a brief title, but descriptive prose explaining the table. The spec provides one example of use of caption:

<caption>
    <p>Table 1.
    <p>This table shows the total score obtained from rolling two
    six-sided dice. The first row represents the value of the first die,
    the first column the value of the second die. The total is given in
    the cell that corresponds to the values of the two dice.
</caption>

This would not make for a good title for the document outline.

I would suggest that you put the <h?> inside the caption if you want it to appear in the document outline. In the example above, this would be suitable:

<caption>
    <h2>Table 1.</h2>
    <p>This table shows the total score obtained from rolling two
    six-sided dice. The first row represents the value of the first die,
    the first column the value of the second die. The total is given in
    the cell that corresponds to the values of the two dice.
</caption>

or in your example:

<table>
    <caption><h2>Results from zombie duck experiment</h2></caption>
    <tr>
        <td>FAILURE</td>
        <td>FAILURE</td>
    </tr>
</table>