first draft of accessibility device section, fixes ##157

index.bs

@@ -810,6 +810,52 @@ You may follow the guidelines for <a href="bfcache">BFCache</a> mentioned above,
 as we expect BFCached and detached documents to be treated the same way,
 with the only difference being that BFCached documents can become [=Document/fully active=] again.
 
+<h3 class=question id="accessibility-devices">
+  Does your feature allow sites to learn about the users use of accessibility devices?
+</h3>
+The Web is designed to work for everyone, and Web standards should be designed
+for people using assistive devices just as much as for users relying
+on mice, keyboards, and touch screens. Accessibility and universal access
+are core to the W3C's mission.
+
+Standards authors though should keep in mind that Web users that rely on
+assistive devices and technologies face some unique risks when using the Web.
+The use of assistive technologies may cause those Web users to stand
+out among other Web users, increasing the risk of unwanted reidentification
+and privacy harm. Similarly, some Web site operators may try to
+discriminate against Web users who rely on assistive devices.
+
+Feature designers and standards authors should therefor be thoughtful and
+careful to limit if, and what, websites can learn about the use off assistive
+technologies. Standards authors must minimize both what inflation about
+accessibility device use their features reveal, both explicitly
+and implicitly. Examples of <em>explicit</em> information about assistive devices
+include device identifiers, model names. Examples of <em>implicit</em>
+information about the use of assistive devices might include
+user interaction patterns that are unlikely to be generated by a
+mouse, keyboard, or touch screen.
+
+<p class=example>
+The [[wai-aria-1.3]] defines additional markup site authors can use to make
+their pages easier to navigate with accessibility devices. The standard
+includes the an [`aria-hidden`](https://w3c.github.io/aria/#aria-hidden)
+attribute, that site authors can use to indicate that certain content
+should be hidden from assistive devices.
+
+A malicious site author might
+abuse the `aria-hidden` attribute to learn if a user is using assistive
+technology, possibly by revealing certain page content to assistive devices,
+while showing very different page content to other users. A malicious
+site author could then possibly infer from the user's behavior which
+content the user was interacting with, and so whether assistive technology
+was being used.
+</p>
+
+
+
+
+
+
 <h3 class=question id="missing-questions">
   What should this questionnaire have asked?
 </h3>

questionnaire.markdown

@@ -38,4 +38,5 @@ For your convenience, a copy of the questionnaire's questions is quoted here in
 >      (instead of getting destroyed) after navigation, and potentially gets reused
 >      on future navigations back to the document?
 > 18.  What happens when a document that uses your feature gets disconnected?
-> 19.  What should this questionnaire have asked?
+> 19.  Does your feature allow sites to learn about the users use of accessibility devices?
+> 20.  What should this questionnaire have asked?