Editorial: I18n considerations for translatable attributes

index.html

@@ -12062,6 +12062,20 @@ <h2>Translatable Attributes</h2>
           <li><pref>aria-rowindextext</pref></li>
           <li><pref>aria-valuetext</pref></li>
         </ul>
+        <p>
+          The web platform does not provide a mechanism to specify language and directionality for a translatable attribute separate from the language and directionality of its containing element. This includes <pref>aria-labelledby</pref> and <pref>aria-describedby</pref> because the <a href="" class="accname">Accessible Name and Description Computation</a> [[ACCNAME-1.2]] results in a flat string.
+        </p>
+        <p>
+          It is best practice for authors to ensure that the language and directionality of the value of a translatable attribute matches the language and directionality of its containing element.
+        </p>
+        <p>
+          Where language or direction metadata for the translatable attribute value needs to differ from that of its containing element, authors can use a referencing attribute, such as <code>aria-labelledby</code>, <code>aria-describedby</code>, or <code>aria-details</code>, pointing to an element, on which language and direction attributes can be expressed directly. This allows translation of these values when the user agent is presenting the document in a machine-translated rendering, via a built-in "Translate this page" feature, as well as appropriate rendering when the element's contents are rendered visually. 
+
+          Authors are encouraged to avoid using plain text ARIA attribute values for text alternatives that contain inline language/direction changes or other text-level markup.
+        </p>
+        <p>
+          For more details, see <a class="informative" href="https://www.w3.org/TR/international-specs#markup_elements_attributes">Internationalization best practices for web developers</a>.
+        </p>
       </section>
       <section id="global_states">
         <h2><dfn>Global</dfn> States and Properties</h2>