diff --git a/dom.bs b/dom.bs
index 2344646f..1232ce20 100644
--- a/dom.bs
+++ b/dom.bs
@@ -1360,15 +1360,15 @@ property of the event being dispatched.
 
 <div algorithm>
 <p>To <dfn export id=concept-event-dispatch>dispatch</dfn> an <var>event</var> to a
-<var>target</var>, with an optional <var>legacy target override flag</var> and an optional
-<var>legacyOutputDidListenersThrowFlag</var>, run these steps:
+<var>target</var>, with an optional <var>legacy target override flag</var> (default false) and an
+optional <var>legacyOutputDidListenersThrowFlag</var>, run these steps:
 
 <ol>
  <li><p>Set <var>event</var>'s <a>dispatch flag</a>.
 
  <li>
   <p>Let <var>targetOverride</var> be <var>target</var>, if <var>legacy target override flag</var>
-  is not given, and <var>target</var>'s <a>associated <code>Document</code></a> otherwise.
+  is true, and <var>target</var>'s <a>associated <code>Document</code></a> otherwise.
   [[!HTML]]
 
   <p class=note><var>legacy target override flag</var> is only used by HTML and only when
@@ -1743,7 +1743,8 @@ and an optional <var>legacyOutputDidListenersThrowFlag</var>, run these steps:
 <div algorithm>
 <p>To <dfn export id=concept-event-fire>fire an event</dfn> named <var>e</var> at <var>target</var>,
 optionally using an <var>eventConstructor</var>, with a description of how IDL attributes are to be
-initialized, and a <var>legacy target override flag</var>, run these steps:
+initialized, an optional boolean <var>legacy target override flag</var> (default false), and an
+optional {{EventTarget}} <var>relatedTarget</var>:
 
 <ol>
  <li><p>If <var>eventConstructor</var> is not given, then let <var>eventConstructor</var> be
@@ -1754,14 +1755,17 @@ initialized, and a <var>legacy target override flag</var>, run these steps:
 
  <li><p>Initialize <var>event</var>'s {{Event/type}} attribute to <var>e</var>.
 
+ <li><p>If <var>relatedTarget</var> is given, then set <var>event</var>'s <a
+ for=Event>relatedTarget</a> to <var>relatedTarget</var>.
+
  <li>
   <p>Initialize any other IDL attributes of <var>event</var> as described in the invocation of this
   algorithm.
 
   <p class=note>This also allows for the {{Event/isTrusted}} attribute to be set to false.
 
- <li><p>Return the result of <a>dispatching</a> <var>event</var> at <var>target</var>, with
- <var>legacy target override flag</var> set if set.
+ <li><p>Return the result of <a>dispatching</a> <var>event</var> at <var>target</var> with
+ <var>legacy target override flag</var>.
 </ol>
 </div>
 
@@ -4936,7 +4940,8 @@ and an optional <a for=/>document</a> <dfn export for="clone a node"><var>docume
    <a for=Element>shadow root</a>'s <a for=ShadowRoot>mode</a>, true, <var>node</var>'s
    <a for=Element>shadow root</a>'s <a for=ShadowRoot>serializable</a>, <var>node</var>'s
    <a for=Element>shadow root</a>'s <a for=ShadowRoot>delegates focus</a>, <var>node</var>'s
-   <a for=Element>shadow root</a>'s <a for=ShadowRoot>slot assignment</a>, and
+   <a for=Element>shadow root</a>'s <a for=ShadowRoot>slot assignment</a>, <var>node</var>'s
+   <a for=Element>shadow root</a>'s <a for=ShadowRoot>reference target</a>, and
    <var>shadowRootRegistry</var>.
 
    <li><p>Set <var>copy</var>'s <a for=Element>shadow root</a>'s <a for=ShadowRoot>declarative</a>
@@ -6553,6 +6558,7 @@ interface ShadowRoot : DocumentFragment {
   readonly attribute boolean clonable;
   readonly attribute boolean serializable;
   readonly attribute Element host;
+  attribute DOMString? referenceTarget;
 
   attribute EventHandler onslotchange;
 };
@@ -6590,6 +6596,9 @@ It is initially set to false.</p>
 <p><a for=/>Shadow roots</a> have an associated <dfn for=ShadowRoot>serializable</dfn> (a boolean).
 It is initially set to false.</p>
 
+<p><a for=/>Shadow roots</a> have an associated <dfn export for=ShadowRoot>reference target</dfn>
+(null or a string). It is initially set to null.
+
 <p><a for=/>Shadow roots</a> have an associated <dfn for=ShadowRoot>custom element registry</dfn>
 (null or a {{CustomElementRegistry}} object). It is initially null.</p>
 
@@ -6628,6 +6637,12 @@ null if <var>event</var>'s <a>composed flag</a> is unset and <a for=/>shadow roo
 <p>The <dfn attribute for=ShadowRoot><code>host</code></dfn> getter steps are to return
 <a>this</a>'s <a for=DocumentFragment>host</a>.
 
+<p>The <dfn attribute for=ShadowRoot><code>referenceTarget</code></dfn> getter steps are to return
+<a>this</a>'s <a for=ShadowRoot>reference target</a>.
+
+<p>The {{ShadowRoot/referenceTarget}} setter
+steps are to set <a>this</a>'s <a for=ShadowRoot>reference target</a> to the given value.
+
 <hr>
 
 <p>The <dfn attribute for=ShadowRoot><code>onslotchange</code></dfn> attribute is an
@@ -6762,6 +6777,7 @@ dictionary ShadowRootInit {
   SlotAssignmentMode slotAssignment = "named";
   boolean clonable = false;
   boolean serializable = false;
+  DOMString? referenceTarget = null;
   CustomElementRegistry? customElementRegistry;
 };
 </pre>
@@ -7738,7 +7754,8 @@ are:
  <var>init</var>["{{ShadowRootInit/mode}}"], <var>init</var>["{{ShadowRootInit/clonable}}"],
  <var>init</var>["{{ShadowRootInit/serializable}}"],
  <var>init</var>["{{ShadowRootInit/delegatesFocus}}"],
- <var>init</var>["{{ShadowRootInit/slotAssignment}}"], and <var>registry</var>.
+ <var>init</var>["{{ShadowRootInit/slotAssignment}}"],
+ <var>init</var>["{{ShadowRootInit/referenceTarget}}"], and <var>registry</var>.
 
  <li><p>Return <a>this</a>'s <a for=Element>shadow root</a>.
 </ol>
@@ -7748,7 +7765,8 @@ are:
 <p>To <dfn id=concept-attach-a-shadow-root>attach a shadow root</dfn>, given an
 <a for=/>element</a> <var>element</var>, a string <var>mode</var>, a boolean <var>clonable</var>,
 a boolean <var>serializable</var>, a boolean <var>delegatesFocus</var>, a string
-<var>slotAssignment</var>, and null or a {{CustomElementRegistry}} object <var>registry</var>:
+<var>slotAssignment</var>, null or a string <var>referenceTarget</var>, and null or a
+{{CustomElementRegistry}} object <var>registry</var>:
 
 <ol>
  <li><p>If <var>element</var>'s <a for=Element>namespace</a> is not the <a>HTML namespace</a>,
@@ -7822,6 +7840,8 @@ a boolean <var>serializable</var>, a boolean <var>delegatesFocus</var>, a string
 
  <li><p>Set <var>shadow</var>'s <a for=ShadowRoot>serializable</a> to <var>serializable</var>.
 
+ <li><p>Set <var>shadow</var>'s <a for=ShadowRoot>reference target</a> to <var>referenceTarget</var>.
+
  <li><p>Set <var>shadow</var>'s <a for=ShadowRoot>custom element registry</a> to
  <var>registry</var>.