contextual role concept proposal

index.html

@@ -184,6 +184,71 @@ <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 id="mapping_contextual">
+      <h3>Exposing HTML Features With Contextual Roles</h3>
+      <p>
+        An element with a <STRONG>contextual role</STRONG> is one whose computed role semantics are based on its ancestral <a>accessibility tree</a> relationship to 
+        another element or elements. Or, an element whose computed role is dependent upon whether it has other associated accessibility information, such as an author-provided accessible name. 
+      </p>
+      <p>
+        For instance, an element that is an <STRONG>accessibility child</STRONG> of its required <STRONG>accessibility parent</STRONG> would expose a computed role for its given context, 
+        such as a list item (`li` element) within an unordered list (`ul` element). However, the same element might be used within a different markup pattern and could therefore expose 
+        different contextually-dependent computed roles, such as a `section` element with an author-provided accessible name (role `region`) versus an unnamed `section` element (role `generic`).
+      </p>
+      <p>
+        When the conditions for an element's contextual role are not met, it will commonly expose a computed role of `generic` or with a <STRONG>minimum role</STRONG>, if applicable. 
+      </p>
+      <div class="note">
+        <p>Previously, the concept of a contextual role was loosely referred to as an element's "scoped" relationship to another element.</p>
+      </div>
+      <div class="example">
+        <p>
+          A <code>li</code> element has an implicit WAI-ARIA role mapping of <code>listitem</code> only when the element is an <STRONG>accessibility child</STRONG> of a 
+          <code>menu</code>, <code>ol</code> or <code>ul</code> element that has not had its `list` role mapping suppressed.
+        </p>
+        <pre><code>&lt;ul>
+    &lt;li>...&lt;/li> &lt;!-- computed role `listitem` -->
+  &lt;/ul> 
+  &lt;article>
+    ...
+    &lt;li>...&lt;/li> &lt;!-- computed role `generic`, not `listitem` -->
+    ...</code></pre>
+      </div>
+      <div class="example">
+        <p>
+          An <code>aside</code> element has an implicit WAI-ARIA role mapping of <code>complementary</code> only when the element is an <STRONG>accessibility child</STRONG> of 
+          the <code>body</code> or <code>main</code> elements, or if the <code>aside</code> has been provided an accessible name.
+        </p>
+        <pre><code>&lt;body>
+  ...
+  &lt;main>
+    ...
+    &lt;article>
+      &lt;aside>...&lt;/aside> &lt;!-- computed role `generic`, not `complementary` -->
+      ...
+      &lt;aside aria-label=named>...&lt;/aside> &lt;!-- computed role `complementary` -->
+    &lt;/article>
+    ...
+    &lt;aside>...&lt;/aside> &lt;!-- computed role `complementary` -->
+  &lt;/main>
+  &lt;aside>...&lt;/aside> &lt;!-- computed role `complementary` -->
+  ...
+  &lt;footer>
+    ...
+    &lt;aside>...&lt;/aside> &lt;!-- computed role `generic`, not `complementary` -->
+  &lt;/footer>
+...</code></pre>
+      </div>
+
+      <div class="example">
+        <p>A <code>section</code> element has an implicit WAI-ARIA role mapping of <code>region</code> only when the element is provided an <STRONG>accessible name</STRONG>.</p>
+        <pre><code>&lt;section title="accessible name">...&lt;/section> &lt;!-- computed role `region` -->
+...
+&lt;section aria-label="accessible name">...&lt;/section> &lt;!-- computed role `region` -->
+...
+&lt;section>...&lt;/section> &lt;!-- computed role `generic`, not `region` --></code></pre>
+      </div>
+    </section>
     <section>
       <h3>HTML Element Role Mappings</h3>
       <ul>