[imsc] Usage pattern for specifying an image's alternate text. (#490)

skynavga has just created a new issue for https://github.com/w3c/imsc:

== Usage pattern for specifying an image's alternate text. ==
IMSC1.1 [1] states that

>A `div` element that contains a child `image` element SHOULD contain a `metadata` element containing an `altText` named metadata item that is a Text Alternative of the image resource referenced by the `image` element.

This is inconsistent with the intended usage shown in TTML2 [2], which would have

```
<div>
  <image ...>
    <ttm:item name="altText">Alternate Text</ttm:item>
  </image>
</div>
```

instead of the current recommendation which would have

```
<div>
  <metadata>
    <ttm:item name="altText">Alternate Text</ttm:item>
  </metadata>
  <image .../>
</div>
```

The problem with this latter usage is that the alternate text is not semantically associated (by document structure) with the `image`, but instead, with the `div`.

Apparently I did not catch this earlier when IMSC1.1 was being published. I would suggest this be addressed in IMSC1.2 by deprecating the current recommendation in favor of a new recommendation based on the first usage example shown above.

[1] https://www.w3.org/TR/ttml-imsc1.1/#image-ttml-image
[2] https://www.w3.org/TR/2018/REC-ttml2-20181108/#xml-lang-example-1

Please view or discuss this issue at https://github.com/w3c/imsc/issues/490 using your GitHub account

Received on Friday, 27 September 2019 09:27:44 UTC