diff --git a/index.bs b/index.bs
index 1966b50..93f1941 100644
--- a/index.bs
+++ b/index.bs
@@ -60,6 +60,8 @@ urlPrefix: https://html.spec.whatwg.org/multipage/; spec: HTML;
     type: dfn; url: #running-script; text: running script;
     type: dfn; url: #muted-errors; for: classic script; text: muted errors;
     type: dfn; url: #cors-cross-origin; text: CORS cross-origin;
+    type: dfn; url: #implied-document; text: implied document;
+    type: dfn: url: #concept-task-document; text: document; for: task;
 urlPrefix: https://tc39.github.io/ecma262/; spec: ECMASCRIPT;
     type: dfn; url: #sec-code-realms; text: JavaScript Realms;
 urlPrefix: https://dom.spec.whatwg.org/; spec: DOM;
@@ -362,6 +364,9 @@ It has the following [=struct/items=]:
 
     : <dfn>pending script</dfn>
     :: Null or a [=script timing info=], initially null.
+
+    : <dfn>script initiated</dfn>
+    :: A boolean, initially false.
 </dl>
 
 <dfn export>script timing info</dfn> is a [=struct=]. It has the following [=struct/items=]:
@@ -415,6 +420,19 @@ Report Long Animation Frames {#loaf-processing-model}
     The <dfn>relevant frame timing info</dfn> for a {{Document}} |document| is its [=nearest same-origin root=]'s [=current frame timing info=].
 </div>
 
+<div algorithm="Record if needed">
+    To <dfn export>start recording task time if needed</dfn> given an [=environment settings object=] |settingsObject|:
+
+    Note: this is called from the [=fire an event=] algorithm and the [=create script entry point=] algorithm.
+    It starts recording frame timing info for the duration of the [=fire an event|event firing=] or [=create script entry point|script=], as if it was a task.
+    This accounts for script and event durations that are not associated with tasks, which would otherwise require an [=implied document=].
+
+    1. If |settingsObject| is not a {{Document}} or its [=relevant frame timing info=] is non-null, then return false.
+    1. [=Record task start time=] given the [=unsafe shared current time=] and |settingsObject|.
+    1. Return true.
+</div>
+
+
 <div algorithm="Record task start time">
     To <dfn export>record task start time</dfn> given a {{DOMHighResTimeStamp}} |unsafeTaskStartTime|, and a {{Document}} |document|:
 
@@ -548,8 +566,8 @@ Report Long Animation Frames {#loaf-processing-model}
         1. If |settings| is not a {{Window}}, then return.
         1. Let |document| be |settings|'s {{Window/document}}.
         1. Let |frameTimingInfo| be |document|'s [=relevant frame timing info=].
-        1. If |frameTimingInfo| is null or if |frameTimingInfo|'s [=frame timing info/pending script=] is not null, then return.
-        1. Assert: |frameTimingInfo|'s [=frame timing info/pending script=]'s [=script timing info/invoker type=] is "`classic-script`".
+        1. [=Assert=]: |frameTimingInfo| is non-null.
+        1. If |frameTimingInfo|'s [=frame timing info/pending script=] is not null, then return.
         1. Set |frameTimingInfo|'s [=frame timing info/pending script=]'s [=script timing info/execution start time=] to the [=unsafe shared current time=].
 </div>
 
@@ -569,8 +587,10 @@ Report Long Animation Frames {#loaf-processing-model}
         1. If |settings| is not a {{Window}}, then return.
         1. Let |document| be |settings|'s {{Window/document}}.
         1. If |document| is not [=fully active=] or	{{Document/hidden}}, then return.
+        1. Let |didStartRecording| be the result of calling [=start recording task time if needed=] given |document|.
         1. Let |frameTimingInfo| be |document|'s [=relevant frame timing info=].
-        1. If |frameTimingInfo| is null, then return.
+        1. [=Assert=]: |frameTimingInfo| is non-null.
+        1. Set |frameTimingInfo|'s [=script initiated=] to |didStartRecording|.
         1. If |frameTimingInfo|'s [=frame timing info/pending script=] is not null, then return.
         1. Let |scriptTimingInfo| be a new [=script timing info=]
             whose [=script timing info/start time=] is the [=unsafe shared current time=],
@@ -588,16 +608,21 @@ Report Long Animation Frames {#loaf-processing-model}
     1. Let |document| be |settings|'s {{Window/document}}.
     1. If |document| is not [=fully active=] or	{{Document/hidden}}, then return.
     1. Let |frameTimingInfo| be |document|'s [=relevant frame timing info=].
+    1. [=Assert=]: |frameTimingInfo| is not null.
     1. Let |scriptTimingInfo| be |frameTimingInfo|'s [=frame timing info/pending script=].
+    1. Let |endTime| be the [=unsafe shared current time=].
     1. Set |frameTimingInfo|'s [=frame timing info/pending script=] to null.
     1. If |scriptTimingInfo| is null, then return.
-    1. Set |scriptTimingInfo|'s [=script timing info/end time=] to the [=unsafe shared current time=].
+    1. Set |scriptTimingInfo|'s [=script timing info/end time=] to |endTime|.
     1. If |script| is a [=classic script=] whose [=classic script/muted errors=] is true, then:
         1. set |scriptTimingInfo|'s [=script timing info/source url=] to the empty string.
         1. set |scriptTimingInfo|'s [=script timing info/source character position=] to -1.
         1. set |scriptTimingInfo|'s [=script timing info/source function name=] to the empty string.
     1. If the [=duration=] between |scriptTimingInfo|'s [=script timing info/start time=] and |scriptTimingInfo|'s [=script timing info/end time=] is greater than 5 milliseconds, then
         [=list/append=] |scriptTimingInfo| to |frameTimingInfo|'s [=frame timing info/scripts=].
+    1. If |frameTimingInfo| is [=frame timing info/script initiated=], then [=record task end time=] given |endTime| and |document|.
+
+        Note: For event listeners, the task lifetime is managed by the [=fire an event=] algorithm, which may invoke multiple listeners to the same event, rather than at the end of a single listener's execution.
 </div>
 
 <div algorithm="Applying source location">
@@ -614,8 +639,8 @@ Report Long Animation Frames {#loaf-processing-model}
     1. If |settings| is not a {{Window}}, then return.
     1. Let |document| be |settings|'s {{Window/document}}.
     1. If |document| is not [=fully active=] or	{{Document/hidden}}, then return.
-    1. Let |frameTimingInfo| be |document|'s [=relevant frame timing info=].
-    1. If |frameTimingInfo| is null, then return.
+    1. Let |frameTimingInfo| be the [=relevant frame timing info=] given |document|.
+    1. Assert: |frameTimingInfo| is not null.
     1. If |frameTimingInfo|'s [=frame timing info/pending script=] is null, then return.
     1. Increment |frameTimingInfo|'s [=frame timing info/pending script=]'s [=script timing info/pause duration=] by the milliseconds value of |duration|.
 </div>