Define concept of minimum role

index.html

@@ -189,13 +189,49 @@ <h3>Exposing HTML Features That Do Not Directly Map to Accessibility APIs</h3>
         <abbr title="application programming interface">API</abbr> properties</a> in the [[core-aam-1.2]].
       </p>
     </section>
+    <section>
+      <h3 id="minimum-role">Exposing HTML Features That Require a Minimum Role</h3>
+      <p>
+        A <dfn>minimum role</dfn> is the equivalent WAI-ARIA role an element will map to if the element does not have a more specific implicit role or 
+        platform role mappings, e.g., a non-generic role. This can help ensure that users of assistive technologies get the best possible experience for 
+        commonly-used and valid HTML markup where otherwise a role would not be exposed.
+      </p>     
+      <p>
+        A minimum role is provided when all of the following conditions are true:
+      </p>
+      <ul>
+        <li>
+          the author has <strong>not</strong> specified a valid explicit WAI-ARIA role to the element, 
+          <strong>or</strong> the specified role is either `none`, `presentation`, or `generic`;
+        </li>
+        <li>
+          the element either has no implicit WAI-ARIA role or platform role mappings, or it has an implicit `generic` or `none` computed role; 
+        </li>
+        <li>
+          and the author has specified attributes which require a minimum role mapping for the element.
+        </li>
+      </ul>
+      <p>
+        The <a href="#html-attribute-state-and-property-mappings">HTML Attribute State and Property Mappings</a> section identifies the specific global attributes which would require
+        an element map to a minimum role.
+      </p>
+      <p>
+        When these conditions are met, the browser MUST expose an object using the mappings defined in CORE-AAM for the specified minimum role.
+        If the element has multiple attributes specified which require a minimum role be returned as the computed role for the element, prioritize 
+        the more specific role in the ARIA taxonomy.
+      </p>
+    </section>
     <section>
       <h3>HTML Element Role Mappings</h3>
       <ul>
         <li>HTML elements with implicit WAI-ARIA role semantics MUST be mapped to platform <a class="termref">accessibility APIs</a> according to the identified WAI-ARIA role mapping as defined in the [[core-aam-1.2]] specification.</li>
-        <li>"Not mapped" means the element does not need to be exposed via an <a class="termref">accessibility API</a>. This is usually because the element is not displayed as part of the user interface. However, authors can force some of these elements to be rendered. For instance, by overriding user agent styles to render elements that would have been otherwise set to `display: none`. In these cases, the user agent SHOULD map such elements to the role of <a class="core-mapping" href="#role-map-generic">`generic`</a>.</li>
-        <li>Where applicable, how an element participates in the computation of its own or another element's <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a> and/or <a data-cite="accname-1.2/#dfn-accessible-description">accessible description</a> is described in the <a href="#accessible-name-and-description-computation">Accessible Name and Description Computation</a> section of this document.</li>
+        <li>"Not mapped" means the element does not need to be exposed via an <a class="termref">accessibility API</a>. This is usually because the element is not displayed as part of the user interface. However, authors can force some of these elements to be rendered. For instance, by overriding user agent styles to render elements that would have been otherwise set to `display: none`. In these cases, the user agent SHOULD map such elements to the role of <a class="core-mapping" href="#role-map-generic">`generic`</a>, unless other HTML features have been specified which would require a more specific <a>minimum role</a> to be exposed.</li>
         <li>Where an element is indicated as having &quot;No corresponding (WAI-ARIA) role&quot;, or is mapped to the <a class="core-mapping" href="#role-map-generic">`generic`</a> role, user agents MUST NOT expose the <a class="core-mapping" href="#ariaRoleDescription">`aria-roledescription`</a> property value in the <a class="termref">accessibility tree</a> unless the element has an explicit, conforming `role` attribute value which [[WAI-ARIA-1.2]] does not prohibit the use of `aria-roledescription`.</li>
+        <li>Some HTML elements expose implicit WAI-ARIA roles depending on whether they have been provided an <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a>. How an element participates in the computation of its own or another element's <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a> and/or <a data-cite="accname-1.2/#dfn-accessible-description">accessible description</a> is described in the <a href="#accessible-name-and-description-computation">Accessible Name and Description Computation</a> section of this document.</li>
+      </ul>
+
+      <h4 id="platform-api-mapping-requirements">Platform API mapping requirements</h4>
+      <ul>
         <li>
           When HTML elements do not have an exact or equivalent mapping to a valid, non-abstract <abbr title="Accessible Rich Internet Applications">WAI-ARIA</abbr> role, a unique `computedrole` string has been specified to serve as the return value for interoperability testing purposes. For instance, the `video` element MAY be exposed with a `computedrole` of "`html-video`". Authors MUST NOT use any `html-`prefixed computed role string in the role attribute (such as `html-video`). User Agents MUST ignore any abstract or invalid role token.
           <div class="example">
@@ -9265,6 +9301,7 @@ <h4 id=att-autofocus>`autofocus`</h4>
     <tr>
       <th>Comments</th>
       <td>
+        Provides a <a href="termref">minimum role</a> of <a class="core-mapping" href="#role-map-group">`group`</a>.
       </td>
     </tr>
   </tbody>
@@ -10866,6 +10903,7 @@ <h4 id=att-draggable>`draggable`</h4>
     <tr>
       <th>Comments</th>
       <td>
+        Provides a <a href="termref">minimum role</a> of <a class="core-mapping" href="#role-map-group">`group`</a>.
       </td>
     </tr>
   </tbody>
@@ -15703,6 +15741,8 @@ <h4 id=att-tabindex>`tabindex`</h4>
     <tr>
       <th>Comments</th>
       <td>
+        <!-- For future consideration:
+        Provides a <a href="termref">minimum role</a> of <a class="core-mapping" href="#role-map-group">`group`</a>. -->
       </td>
     </tr>
   </tbody>