add none

index.bs

@@ -393,6 +393,17 @@ spec: RFC8941; urlPrefix: https://datatracker.ietf.org/doc/html/rfc8941#
       by default in [=child navigables=] whose [=navigable/active
       document|document=] is cross-origin with its [=navigable/parent=]'s
       [=navigable/active document|document=].</dd>
+      <dt><dfn for="default allowlist" export><code>none</code></dfn></dt>
+      <dd>The feature is not allowed in {{Document}}s in [=/top-level
+      traversables=] by default, as well as those in all [=child
+      navigables=].  It can be allowed {{Document}}s in [=/top-level
+      traversables=] by delivering the {{Document}} with a suitable <a
+      http-header> `Permissions-Policy`</a> header). It can be allowed
+      in in [=child navigables=] if it allowed in the parent
+      {{Document}} by explicitly supplying a [=container policy=] on
+      the [=navigable container=] that overrides this default and by
+      delivering the {{Document}} with a suitable <a
+      http-header>`Permissions-Policy`</a> header.</dd>
     </dl>
   </section>
 </section>