Re: Comments on SVG Accessibility Mappings -- Default and Allowed Semantics

Another follow-up.

If `<title>` is NOT used as (part of) the ARIA name for its parent because
of ARIA labelling attributes, it SHOULD be included in the accessibility
tree with the role of "tooltip", to match its function on a visible display.

This would correspond with advice to authors: Use <title> to label an
element, except when the <title> value is used for a tooltip that does not
make an effective name, in which case add an `aria-label` or
`aria-labelledby` attribute.  However, in this case we still want the
tooltip information to be available to AT users!

An example would be the following very simple bar chart.  The `<title>`
elements on the bars are used as tooltips to give the exact numerical value
of each bar.  The natural label for each bar, however, is the label from
the x-axis:

<svg viewBox="0 0 100 120">
  <rect id="bar1" aria-labelledby="label1"
        x="10" y="50" height="50" width="30" fill="red">
       <title>50%</title>
  </rect>
  <rect id="bar2" aria-labelledby="label2"
        x="60" y="30" height="70"  width="30" fill="blue">
       <title>70%</title>
  </rect>
  <line x1="0" x2="100" y1="100" y2="100" stroke="black" />
  <g  text-anchor="middle" font-size="10">
  <text id="label1" x="25"
        y="100" dy="1em">Team A</text>
  <text id="label2" x="75"
        y="100" dy="1em">Team B</text>
</svg>

Live Example:

   - http://codepen.io/AmeliaBR/pen/WbOREM

Or view it full page if you want to test it with current ATs, without all
the code being read back to you:

   - http://codepen.io/AmeliaBR/full/WbOREM/


I don't know what, if anything, should be done with <desc> elements if the
author has included both a <desc> and something else linked with
aria-describedby.  The content of <desc> is not available through normal
use of the SVG, so I guess the most consistent behavior is also to ignore
it for accessibility APIs.

--Amelia BR