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Co-authored-by: Martin Thomson <mt@lowentropy.net>

fullscreen.bs

@@ -688,9 +688,9 @@ iframe:fullscreen {
 
 
 
-<h2 id="keyboard-locking">keyboard locking</h2>
+<h2 id="keyboard-locking">Keyboard Locking</h2>
 
-<p>keyboard Locking enhances the functionality of web applications running in fullscreen by allowing
+<p>Keyboard locking enhances the functionality of web applications running in fullscreen by allowing
 them to intercept certain key inputs that would typically be handled by either the system or the
 user agent. This is useful in scenarios such as gaming or remote desktop applications, where keys
 like ESC or function keys are integral to the application's functionality.
@@ -704,20 +704,26 @@ web application in fullscreen.
 
 <dl>
   <dt><dfn>Application-level keyboard lock</dfn></dt>
-  <dd><p>Captures all keys that the user agent would ordinarily receive, except those reserved for
-  critical system functions or security shortcuts (e.g., Ctrl+Alt+Del).
+  <dd><p>Captures all keys that the user agent would ordinarily receive, such as those that open or
+  close windows. This excludes those reserved for system-level interactions, such
+  as key presses that open system menus or switch applications.
   <dt><dfn>System-level keyboard lock</dfn></dt>
   <dd><p>Capture a wider range of keys, including those used for system-level navigation and
   shortcuts (e.g., Alt+Tab), subject to user consent and user agent implementation.
 </dl>
 
+<p>User agents should reserve an additional input for the purposes of exiting fullscreen.
+There are also some system-level key sequences or combinations that cannot be
+intercepted for security reasons, such as Ctrl+Alt+Del on Windows.
+
 <div algorithm>
   <p>To <dfn>run the release the keyboard lock steps</dfn> for a <a>document</a>
   <var>document</var>, run these steps:
   <ol>
     <li><p>If the [=keyboard lock flag=] for the <var>document</var> is not set, abort these steps.
     <li><p>Deactivate the keyboard lock and restore the handling of keyboard inputs to the default
-    behavior of the user agent and the operating system. <li><p>Set the [=keyboard lock flag=] for
+    behavior of the user agent and the operating system.
+    <li><p>Set the [=keyboard lock flag=] for
     the <var>document</var> to <code>false</code>.
   </ol>
 </div>