diff --git a/index.html b/index.html
index 57963d3..0ef0762 100644
--- a/index.html
+++ b/index.html
@@ -47,11 +47,11 @@
         specification, exposes the current type and angle of the device's
         screen orientation, and dispatches events when it changes. This enables
         web applications to programmatically adapt the user experience for
-        multiple screen orientations, working alongside CSS. The API also
-        allows for the screen orientation to be locked under certain
-        preconditions. This is particularly useful for applications such as
-        computer games, where users physically rotate the device, but the
-        screen orientation itself should not change.
+        multiple screen orientations, working alongside CSS. This API is
+        particularly useful for applications such as computer games, where
+        users physically rotate the device, but the screen orientation itself
+        should not change. The API restricts locking the screen orientation
+        only if certain [=pre-lock conditions=] are met.
       </p>
     </section>
     <section id="sotd">
@@ -393,17 +393,19 @@ <h2>
         <h2>
           `lock()` method
         </h2>
+        <p>
+          <dfn>pre-lock conditions</dfn> are optional requirements that a
+          [=user agent=] MAY impose before allowing screen orientation locking.
+          Common pre-lock conditions include requiring the document to be in
+          fullscreen mode or being part of an installed web application. See
+          [[[#appmanifest-interaction]]] and [[[#fullscreen-interaction]]] for
+          specific examples.
+        </p>
         <p>
           When the {{lock()}} method is invoked with {{OrientationLockType}}
           |orientation:OrientationLockType|, the [=user agent=] MUST run the
           following steps.
         </p>
-        <p>
-          The [=user agent=] MAY require a [=document=] and its associated
-          [=Document/browsing context=] to meet one or more <dfn>pre-lock
-          conditions</dfn> in order to [=lock the screen orientation=]. See
-          [[[#appmanifest-interaction]]] and [[[#fullscreen-interaction]]].
-        </p>
         <ol class="algorithm">
           <li>Let |document:Document| be [=this=]'s [=relevant global
           object=]'s [=associated `Document`=].
@@ -416,6 +418,12 @@ <h2>
           orientation to |orientation|, return [=a promise rejected with=] a
           {{"NotSupportedError"}} {{DOMException}} and abort these steps.
           </li>
+          <li>If the [=user agent=] requires |document| and its associated
+          [=Document/browsing context=] to meet [=pre-lock conditions=] in
+          order to [=lock the screen orientation=], and those conditions are
+          not met, return [=a promise rejected with=] a {{"NotAllowedError"}}
+          {{DOMException}} and abort these steps.
+          </li>
           <li data-tests="lock-basic.html">If |document|'s
           {{Document/[[orientationPendingPromise]]}} is not `null`, [=reject
           and nullify the current lock promise=] of |document| with an