From 21b8a2c916a39d76ce433b93addd47461a8e1b73 Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Wed, 18 Sep 2024 13:30:18 -0700
Subject: [PATCH 01/25] Define the `<selectedoption>` element

The `<selectedoption>` element is part of the customizable `<select>`
proposal: https://github.com/whatwg/html/issues/9799

It allows authors to declaratively clone the contents of the currently
selected `<option>` of a `<select>` and style it independently for use
in a base appearance `<select>`'s button.

The timing of cloning has been discussed here:
https://github.com/whatwg/html/issues/10520

The selectedoption element has been discussed generally here:
https://github.com/w3c/csswg-drafts/issues/10242
---
 source | 181 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 181 insertions(+)

diff --git a/source b/source
index de407dd6dc0..200d049fc6e 100644
--- a/source
+++ b/source
@@ -1794,6 +1794,9 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
    <span>stack of open elements</span> of an <span>HTML parser</span>, then
    <span>process internal resource links</span> given <var>insertedNode</var>'s
    <span>node document</span>.</p></li>
+
+   <li><p>Run <span>maybe clone option into selectedoption</span> given
+   <var>insertedNode</var>.</p></li>
   </ol>
 
   <p>The <span data-x="concept-node-remove-ext">removing steps</span> for the HTML Standard, given
@@ -1838,6 +1841,9 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
    <li><p>If <var>removedNode</var>'s <code data-x="attr-popover">popover</code> attribute is not in
    the <span data-x="attr-popover-none-state">no popover state</span>, then run the <span>hide
    popover algorithm</span> given <var>removedNode</var>, false, false, and false.</p></li>
+
+   <li><p>Run <span>maybe clone option into selectedoption</span> given
+   <var>oldParent</var>.</p></li>
   </ol>
 
   <p>A <dfn id="insert-an-element-into-a-document" data-x="node is inserted into a document"
@@ -3201,6 +3207,7 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
      <li><dfn data-x="dom-Element-id" data-x-href="https://dom.spec.whatwg.org/#dom-element-id"><code>id</code></dfn> attribute</li>
      <li><dfn data-x="dom-Element-setAttribute" data-x-href="https://dom.spec.whatwg.org/#dom-element-setattribute"><code>setAttribute()</code></dfn> method</li>
      <li><dfn data-x-href="https://dom.spec.whatwg.org/#dom-node-textcontent"><code>textContent</code></dfn> attribute</li>
+     <li><dfn data-x="dom-parentnode-replacechildren" data-x-href="https://dom.spec.whatwg.org/#dom-parentnode-replacechildren"><code>replaceChildren()</code></dfn> method</li>
 
      <li>The <dfn data-x-href="https://dom.spec.whatwg.org/#concept-tree">tree</dfn>, <dfn data-x-href="https://dom.spec.whatwg.org/#concept-shadow-tree">shadow tree</dfn>, and <dfn data-x-href="https://dom.spec.whatwg.org/#concept-node-tree">node tree</dfn> concepts</li>
      <li>The <dfn data-x-href="https://dom.spec.whatwg.org/#concept-tree-order">tree order</dfn> and <dfn data-x-href="https://dom.spec.whatwg.org/#concept-shadow-including-tree-order">shadow-including tree order</dfn> concepts</li>
@@ -3208,6 +3215,7 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
      <li>The <dfn data-x-href="https://dom.spec.whatwg.org/#concept-tree-child" data-x="concept-tree-child">child</dfn> concept</li>
      <li>The <dfn data-x-href="https://dom.spec.whatwg.org/#concept-tree-root">root</dfn> and <dfn data-x-href="https://dom.spec.whatwg.org/#concept-shadow-including-root">shadow-including root</dfn> concepts</li>
      <li>The <dfn data-x-href="https://dom.spec.whatwg.org/#concept-tree-inclusive-ancestor">inclusive ancestor</dfn>,
+             <dfn data-x-href="https://dom.spec.whatwg.org/#concept-tree-ancestor">ancestor</dfn>,
              <dfn data-x-href="https://dom.spec.whatwg.org/#concept-tree-descendant">descendant</dfn>,
              <dfn data-x="concept-shadow-including-ancestor" data-x-href="https://dom.spec.whatwg.org/#concept-shadow-including-ancestor">shadow-including ancestor</dfn>,
              <dfn data-x-href="https://dom.spec.whatwg.org/#concept-shadow-including-descendant">shadow-including descendant</dfn>,
@@ -53304,6 +53312,9 @@ interface <dfn interface>HTMLSelectElement</dfn> : <span>HTMLElement</span> {
   element, and all the <code>option</code> element children of all the <code>optgroup</code> element
   children of the <code>select</code> element, in <span>tree order</span>.</p>
 
+  <p>Every <code>select</code> element has <dfn>select descendant selectedoption elements</dfn>,
+  which is a <span>list</span> of <code>selectedoption</code> elements, initially « ».</p>
+
   <p>The <dfn element-attr for="select"><code data-x="attr-select-required">required</code></dfn>
   attribute is a <span>boolean attribute</span>. When specified, the user will be required to select
   a value before submitting the form.</p>
@@ -54156,6 +54167,61 @@ interface <dfn interface>HTMLOptionElement</dfn> : <span>HTMLElement</span> {
 
   </div>
 
+  <p>To get the <dfn>option element ancestor select</dfn> given an <code>option</code>
+  <var>option</var>:</p>
+
+  <ol>
+   <li>
+    <p>For each <var>ancestor</var> of <var>option</var>'s <span
+    data-x="ancestor">ancestors</span>:</p>
+
+    <ol>
+     <li><p>If <var>ancestor</var> is a <code>select</code>, then return
+     <var>ancestor</var>.</p></li>
+    </ol>
+   </li>
+
+   <li><p>Return null.</p></li>
+  </ol>
+
+  <p>To <dfn>maybe clone option into selectedoption</dfn>, given an <code>Element</code>
+  <var>element</var>:</p>
+
+  <ol>
+   <li>
+    <p>For each <var>ancestor</var> of <var>element</var>'s <span
+    data-x="ancestor">ancestors</span>:</p>
+
+    <ol>
+     <li>
+      <p>If all of the following conditions are true:</p>
+
+      <ul>
+       <li><p><var>ancestor</var> is an <code>option</code> element;</p></li>
+
+       <li><p><var>ancestor</var> has a non-null <span>option element ancestor
+       select</span>;</p></li>
+
+       <li><p><var>ancestor</var>'s <span>option element ancestor select</span> is rendered as a
+       <span>drop-down box</span>;</p></li>
+
+       <li><p><var>ancestor</var>'s <span data-x="concept-option-selectedness">selectedness</span>
+       is true,</p></li>
+      </ul>
+
+      <p>then for each <var>selectedoption</var> of <var>ancestor</var>'s <span>option element
+      ancestor select</span>'s <span>select descendant selectedoption elements</span>, run
+      <span>clone an option into a selectedoption</span> given <var>ancestor</var> and
+      <var>selectedoption</var>.</p>
+     </li>
+    </ol>
+   </li>
+  </ol>
+
+  <p>Whenever an <code>option</code> <var>option</var>'s <span
+  data-x="concept-option-selectedness">selectedness</span> is set to true, run <span>maybe clone
+  option into selectedoption</span> given <var>option</var>.</p>
+
   <dl class="domintro">
    <dt><code data-x=""><var>option</var>.<span subdfn data-x="dom-option-selected">selected</span></code></dt>
 
@@ -55816,6 +55882,121 @@ interface <dfn interface>HTMLLegendElement</dfn> : <span>HTMLElement</span> {
 
   </div>
 
+  <h4>The <dfn element><code>selectedoption</code></dfn> element</h4>
+
+  <p>The <code>selectedoption</code> element reflects the contents of a <code>select</code>
+  element's currently selected <code>option</code> element. <code>selectedoption</code> elements can
+  be used to declaratively show the selected <code>option</code> element's contents in a different
+  part of the document, such as the <code>select</code> element's invoker button, with alternate
+  rendering based on different selectors in the author's stylesheet.</p>
+
+  <p>Every time the selected <code>option</code> of a <code>select</code> switches from one option
+  to another, or the currently selected <code>option</code>'s descendant DOM structure mutates, the
+  <code>selectedoption</code> element removes all of its children and replaces them with a new
+  cloned copy of the DOM structure of the <code>select</code>'s selected <code>option</code>
+  element.</p>
+
+  <p><code>selectedoption</code> elements become associated with <code>select</code> elements when
+  the <code>selectedoption</code> is a <span>descendant</span> of the <code>select</code>.</p>
+
+  <p>To <dfn>clone an option into a selectedoption</dfn>, given an <code>option</code> element
+  <var>option</var> and a <code>selectedoption</code> element <var>selectedOption</var>:</p>
+
+  <ol>
+   <li><p>Let <var>nodes</var> be « ».</p></li>
+
+   <li>
+    <p>If <var>option</var> is not null, then for each <var>child</var> of <var>option</var>'s <span
+    data-x="concept-tree-child">children</span>:</p>
+
+    <ol>
+     <li><p>Let <var>childClone</var> be the result of running <span
+     data-x="concept-node-clone">clone</span> given <var>child</var>, null, true.</p></li>
+
+     <li><p><span data-x="list append">Append</span> <var>childClone</var> to
+     <var>nodes</var>.</p></li>
+    </ol>
+   </li>
+
+   <li><p>Run <span data-x="dom-parentnode-replacechildren">replaceChildren</span> on
+   <var>selectedOption</var> given <var>nodes</var>.</p></li>
+  </ol>
+
+  <p>The <code>selectedoption</code> <span>HTML element insertion steps</span>, given
+  <var>selectedoption</var>, are:</p>
+
+  <ol>
+   <li><p>Let <var>firstAncestorSelect</var> be null.</p></li>
+
+   <li><p>Let <var>ancestor</var> be <var>selectedoption</var>'s <span>parent</span>.</p></li>
+
+   <li>
+    <p><span>While</span> <var>firstAncestorSelect</var> is null and <var>ancestor</var> is not
+    null:</p>
+
+    <ol>
+     <li><p>If <var>ancestor</var> is a <code>select</code> element, then set
+     <var>firstAncestorSelect</var> to <var>ancestor</var>.</p></li>
+
+     <li><p>Set <var>ancestor</var> to <var>ancestor</var>'s <span>parent</span>.</p></li>
+    </ol>
+   </li>
+
+   <li><p>If <var>firstAncestorSelect</var> is null, then return.</p></li>
+
+   <li><p><span data-x="list append">Append</span> <var>selectedoption</var> to
+   <var>firstAncestorSelect</var>'s <span>select descendant selectedoption elements</span>.</p></li>
+
+   <li><p>Run <span>clone an option into a selectedoption</span> given the first <code>option</code>
+   in <var>firstAncestorSelect</var>'s <span data-x="concept-select-option-list">list of
+   options</span> whose <span data-x="concept-option-selectedness">selectedness</span> is true and
+   <var>insertedNode</var>.</p></li>
+  </ol>
+
+  <p>The <code>selectedoption</code> <span>HTML element removing steps</span>, given
+  <var>selectedoption</var> and <var>oldParent</var>, are:</p>
+
+  <ol>
+   <li>
+    <p>For each <var>ancestor</var> of <var>selectedoption</var>'s <span
+    data-x="ancestor">ancestors</span>:</p>
+
+    <ol>
+     <li><p>If <var>ancestor</var> is a <code>select</code> element, then return.</p></li>
+    </ol>
+   </li>
+
+   <li>
+    <p>For each <var>ancestor</var> of <var>oldParent</var>'s <span data-x="inclusive
+    ancestor">inclusive ancestors</span>:</p>
+
+    <ol>
+     <li>
+      <p>If <var>ancestor</var> is a <code>select</code> element, then:</p>
+
+      <ol>
+       <li><p><span data-x="list remove">remove</span> <var>selectedoption</var> from
+       <var>ancestor</var>'s <span>select descendant selectedoption elements</span>.</p></li>
+
+       <li><p>Run <span>clone an option into a selectedoption</span> given null and
+       <var>selectedoption</var>.</p></li>
+
+       <li><p>Return.</p></li>
+      </ol>
+     </li>
+    </ol>
+   </li>
+  </ol>
+
+  <p>The following <span data-x="concept-element-attributes-change-ext">attribute change
+  steps</span>, given <var>element</var>, <var>localName</var>, <var>oldValue</var>,
+  <var>value</var>, and <var>namespace</var> are used for all <span>HTML elements</span> in order to
+  support <code>selectedoption</code> elements:</p>
+
+  <ol>
+   <li><p>Run <span>maybe clone option into selectedoption</span> given <var>element</var>.</p></li>
+  </ol>
+
 
 
   <h4 split-filename="form-control-infrastructure">Form control infrastructure</h4>

From 1aece114fda3a5a318730c4056a92d10c56f0f73 Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Fri, 27 Sep 2024 10:13:16 -0700
Subject: [PATCH 02/25] add dl

---
 source | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/source b/source
index 200d049fc6e..a3909a156c7 100644
--- a/source
+++ b/source
@@ -55884,6 +55884,30 @@ interface <dfn interface>HTMLLegendElement</dfn> : <span>HTMLElement</span> {
 
   <h4>The <dfn element><code>selectedoption</code></dfn> element</h4>
 
+  <dl class="element">
+   <dt><span data-x="concept-element-categories">Categories</span>:</dt>
+   <dd>None.</dd>
+   <dt><span data-x="concept-element-contexts">Contexts in which this element can be used</span>:</dt>
+   <dd>As a descendant of a <code>button</code> element which is a child of a <code>select</code>
+   element.</dd>
+   <dt><span data-x="concept-element-content-model">Content model</span>:</dt>
+   <dd><span data-x="concept-content-nothing">Nothing</span>.</dd>
+   <dt><span data-x="concept-element-attributes">Content attributes</span>:</dt>
+   <dd><span>Global attributes</span></dd>
+   <dt><span
+   data-x="concept-element-accessibility-considerations">Accessibility considerations</span>:</dt>
+   <dd><a href="https://w3c.github.io/html-aria/#el-selectedoption">For authors</a>.</dd>
+   <dd><a href="https://w3c.github.io/html-aam/#el-selectedoption">For implementers</a>.</dd>
+   <dt><span data-x="concept-element-dom">DOM interface</span>:</dt>
+   <dd w-nodev>
+    <pre><code class="idl">[Exposed=Window]
+interface <dfn interface>HTMLSelectedOptionElement</dfn> : <span>HTMLElement</span> {
+  [<span>HTMLConstructor</span>] constructor();
+};</code></pre>
+   </dd>
+   <dd w-dev>Uses <code>HTMLSelectedOptionElement</code>.</dd>
+  </dl>
+
   <p>The <code>selectedoption</code> element reflects the contents of a <code>select</code>
   element's currently selected <code>option</code> element. <code>selectedoption</code> elements can
   be used to declaratively show the selected <code>option</code> element's contents in a different

From a1bd1e81d0b8f29372c14089fd4652f68859b601 Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Fri, 27 Sep 2024 10:19:00 -0700
Subject: [PATCH 03/25] index

---
 source | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/source b/source
index a3909a156c7..abbcb09c252 100644
--- a/source
+++ b/source
@@ -139902,6 +139902,16 @@ interface <dfn interface>External</dfn> {
      <td><code>HTMLSelectElement</code></td>
     </tr>
 
+    <tr>
+     <th><code>selectedoption</code></th>
+     <td>Mirrors content from an <code>option</code></td>
+     <td>none</td>
+     <td><code>button</code></td>
+     <td>empty</td>
+     <td><span data-x="global attributes">globals</span></td>
+     <td><code>HTMLSelectedOptionElement</code></td>
+    </tr>
+
     <tr>
      <th><code>slot</code></th>
      <td>Shadow tree slot</td>
@@ -142687,6 +142697,10 @@ interface <dfn interface>External</dfn> {
      <td> <code>select</code>
      <td> <code>HTMLSelectElement</code> : <code>HTMLElement</code>
 
+    <tr>
+     <td> <code>selectedoption</code>
+     <td> <code>HTMLSelectedOptionelement</code> : <code>HTMLElement</code>
+
     <tr>
      <td> <code>slot</code>
      <td> <code>HTMLSlotElement</code> : <code>HTMLElement</code>

From c04ca1876d9ca21bc1e4bd2cdd0d7e10b77d8c43 Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Fri, 4 Oct 2024 11:38:48 -0700
Subject: [PATCH 04/25] inline replacechildren

---
 source | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/source b/source
index abbcb09c252..10cb5ca157c 100644
--- a/source
+++ b/source
@@ -3207,7 +3207,6 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
      <li><dfn data-x="dom-Element-id" data-x-href="https://dom.spec.whatwg.org/#dom-element-id"><code>id</code></dfn> attribute</li>
      <li><dfn data-x="dom-Element-setAttribute" data-x-href="https://dom.spec.whatwg.org/#dom-element-setattribute"><code>setAttribute()</code></dfn> method</li>
      <li><dfn data-x-href="https://dom.spec.whatwg.org/#dom-node-textcontent"><code>textContent</code></dfn> attribute</li>
-     <li><dfn data-x="dom-parentnode-replacechildren" data-x-href="https://dom.spec.whatwg.org/#dom-parentnode-replacechildren"><code>replaceChildren()</code></dfn> method</li>
 
      <li>The <dfn data-x-href="https://dom.spec.whatwg.org/#concept-tree">tree</dfn>, <dfn data-x-href="https://dom.spec.whatwg.org/#concept-shadow-tree">shadow tree</dfn>, and <dfn data-x-href="https://dom.spec.whatwg.org/#concept-node-tree">node tree</dfn> concepts</li>
      <li>The <dfn data-x-href="https://dom.spec.whatwg.org/#concept-tree-order">tree order</dfn> and <dfn data-x-href="https://dom.spec.whatwg.org/#concept-shadow-including-tree-order">shadow-including tree order</dfn> concepts</li>
@@ -3328,6 +3327,8 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
      <li><dfn data-x-href="https://dom.spec.whatwg.org/#abortcontroller-signal-abort">signal abort</dfn></li>
      <li><dfn data-x="AbortSignal-add" data-x-href="https://dom.spec.whatwg.org/#abortsignal-add">add</dfn></li>
      <li>The <dfn data-x-href="https://dom.spec.whatwg.org/#concept-element-attributes-get-by-name">get an attribute by name</dfn> algorithm</li>
+     <li>The <dfn data-x-href="https://dom.spec.whatwg.org/#concept-node-ensure-pre-insertion-validity">ensure pre-insertion validity</dfn> algorithm</li>
+     <li>The <dfn data-x-href="https://dom.spec.whatwg.org/#converting-nodes-into-a-node">convert nodes into a node</dfn> algorithm</li>
     </ul>
 
     <p>The following features are defined in <cite>UI Events</cite>: <ref>UIEVENTS</ref></p>
@@ -55942,8 +55943,14 @@ interface <dfn interface>HTMLSelectedOptionElement</dfn> : <span>HTMLElement</sp
     </ol>
    </li>
 
-   <li><p>Run <span data-x="dom-parentnode-replacechildren">replaceChildren</span> on
-   <var>selectedOption</var> given <var>nodes</var>.</p></li>
+   <li><p>Let <var>convertedNode</var> be the result of <span>convert nodes into a node</span> given
+   <var>nodes</var> and <var>option</var>'s <span>node document</span>.</p></li>
+
+   <li><p><span>Ensure pre-insertion validity</span> of <var>convertedNode</var> into
+   <var>selectedOption</var> before null</p></li>
+
+   <li><p><span data-x="concept-node-replace-all">Replace all</span> with <var>convertedNode</var>
+   within <var>selectedOption</var>.</p></li>
   </ol>
 
   <p>The <code>selectedoption</code> <span>HTML element insertion steps</span>, given

From 09777e2b104ff1893830672d210466b10b3415d0 Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Fri, 4 Oct 2024 11:56:42 -0700
Subject: [PATCH 05/25] update content model of button element

---
 source | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/source b/source
index 10cb5ca157c..4124f51ac24 100644
--- a/source
+++ b/source
@@ -53000,6 +53000,8 @@ You cannot submit this form when the field is incorrect.</samp></pre>
    <dd><span>Phrasing content</span>, but there must be no <span>interactive content</span>
    descendant and no descendant with the <code data-x="attr-tabindex">tabindex</code> attribute
    specified.</dd>
+   <dd>If the element is the first child of a <code>select</code> element, then it must have one
+   <code>selectedoption</code> element.</dd>
    <dt><span data-x="concept-element-attributes">Content attributes</span>:</dt>
    <dd><span>Global attributes</span></dd>
    <dd><code data-x="attr-fe-disabled">disabled</code></dd>

From c846c3ef504e05f688a27a4273dc0ea9f02a5f7d Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Mon, 4 Nov 2024 09:21:27 -0800
Subject: [PATCH 06/25] add clear a selectedoption

---
 source | 26 ++++++++++++++++++++------
 1 file changed, 20 insertions(+), 6 deletions(-)

diff --git a/source b/source
index 4124f51ac24..06c65d83455 100644
--- a/source
+++ b/source
@@ -55933,7 +55933,7 @@ interface <dfn interface>HTMLSelectedOptionElement</dfn> : <span>HTMLElement</sp
    <li><p>Let <var>nodes</var> be « ».</p></li>
 
    <li>
-    <p>If <var>option</var> is not null, then for each <var>child</var> of <var>option</var>'s <span
+    <p>For each <var>child</var> of <var>option</var>'s <span
     data-x="concept-tree-child">children</span>:</p>
 
     <ol>
@@ -55955,6 +55955,15 @@ interface <dfn interface>HTMLSelectedOptionElement</dfn> : <span>HTMLElement</sp
    within <var>selectedOption</var>.</p></li>
   </ol>
 
+  <p>To <dfn>clear a selectedoption</dfn> given a <code>selectedoption</code> element
+  <var>selectedoption</var>:</p>
+
+  <ol>
+   <li><p><span data-x="concept-node-remove-ext">Remove</span> all <span
+   data-x="concept-tree-child">children</span> of <var>selectedoption</var>, in <span>tree
+   order</span></p></li>
+  </ol>
+
   <p>The <code>selectedoption</code> <span>HTML element insertion steps</span>, given
   <var>selectedoption</var>, are:</p>
 
@@ -55980,10 +55989,16 @@ interface <dfn interface>HTMLSelectedOptionElement</dfn> : <span>HTMLElement</sp
    <li><p><span data-x="list append">Append</span> <var>selectedoption</var> to
    <var>firstAncestorSelect</var>'s <span>select descendant selectedoption elements</span>.</p></li>
 
-   <li><p>Run <span>clone an option into a selectedoption</span> given the first <code>option</code>
-   in <var>firstAncestorSelect</var>'s <span data-x="concept-select-option-list">list of
-   options</span> whose <span data-x="concept-option-selectedness">selectedness</span> is true and
+   <li><p>Let <var>option</var> be the first <code>option</code> in <var>firstAncestorSelect</var>'s
+   <span data-x="concept-select-option-list">list of options</span> whose <span
+   data-x="concept-option-selectedness">selectedness</span> is true if any such <code>option</code>
+   exists, otherwise null.</p></li>
+
+   <li><p>If <var>option</var> is null, then run <span>clear a selectedoption</span> given
    <var>insertedNode</var>.</p></li>
+
+   <li><p>Otherwise, run <span>clone an option into a selectedoption</span> given <var>option</var>
+   and <var>insertedNode</var>.</p></li>
   </ol>
 
   <p>The <code>selectedoption</code> <span>HTML element removing steps</span>, given
@@ -56011,8 +56026,7 @@ interface <dfn interface>HTMLSelectedOptionElement</dfn> : <span>HTMLElement</sp
        <li><p><span data-x="list remove">remove</span> <var>selectedoption</var> from
        <var>ancestor</var>'s <span>select descendant selectedoption elements</span>.</p></li>
 
-       <li><p>Run <span>clone an option into a selectedoption</span> given null and
-       <var>selectedoption</var>.</p></li>
+       <li><p>Run <span>clear a selectedoption</span> given <var>selectedoption</var>.</p></li>
 
        <li><p>Return.</p></li>
       </ol>

From bef82d0bc49e0aa86c7265ce60823402140b8a25 Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Mon, 4 Nov 2024 09:25:26 -0800
Subject: [PATCH 07/25] nits

---
 source | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/source b/source
index 06c65d83455..9c7096948a6 100644
--- a/source
+++ b/source
@@ -55949,7 +55949,7 @@ interface <dfn interface>HTMLSelectedOptionElement</dfn> : <span>HTMLElement</sp
    <var>nodes</var> and <var>option</var>'s <span>node document</span>.</p></li>
 
    <li><p><span>Ensure pre-insertion validity</span> of <var>convertedNode</var> into
-   <var>selectedOption</var> before null</p></li>
+   <var>selectedOption</var> before null.</p></li>
 
    <li><p><span data-x="concept-node-replace-all">Replace all</span> with <var>convertedNode</var>
    within <var>selectedOption</var>.</p></li>
@@ -55968,31 +55968,32 @@ interface <dfn interface>HTMLSelectedOptionElement</dfn> : <span>HTMLElement</sp
   <var>selectedoption</var>, are:</p>
 
   <ol>
-   <li><p>Let <var>firstAncestorSelect</var> be null.</p></li>
+   <li><p>Let <var>nearestSelectAncestor</var> be null.</p></li>
 
    <li><p>Let <var>ancestor</var> be <var>selectedoption</var>'s <span>parent</span>.</p></li>
 
    <li>
-    <p><span>While</span> <var>firstAncestorSelect</var> is null and <var>ancestor</var> is not
+    <p><span>While</span> <var>nearestSelectAncestor</var> is null and <var>ancestor</var> is not
     null:</p>
 
     <ol>
      <li><p>If <var>ancestor</var> is a <code>select</code> element, then set
-     <var>firstAncestorSelect</var> to <var>ancestor</var>.</p></li>
+     <var>nearestSelectAncestor</var> to <var>ancestor</var>.</p></li>
 
      <li><p>Set <var>ancestor</var> to <var>ancestor</var>'s <span>parent</span>.</p></li>
     </ol>
    </li>
 
-   <li><p>If <var>firstAncestorSelect</var> is null, then return.</p></li>
+   <li><p>If <var>nearestSelectAncestor</var> is null, then return.</p></li>
 
    <li><p><span data-x="list append">Append</span> <var>selectedoption</var> to
-   <var>firstAncestorSelect</var>'s <span>select descendant selectedoption elements</span>.</p></li>
+   <var>nearestSelectAncestor</var>'s <span>select descendant selectedoption
+   elements</span>.</p></li>
 
-   <li><p>Let <var>option</var> be the first <code>option</code> in <var>firstAncestorSelect</var>'s
-   <span data-x="concept-select-option-list">list of options</span> whose <span
-   data-x="concept-option-selectedness">selectedness</span> is true if any such <code>option</code>
-   exists, otherwise null.</p></li>
+   <li><p>Let <var>option</var> be the first <code>option</code> in
+   <var>nearestSelectAncestor</var>'s <span data-x="concept-select-option-list">list of
+   options</span> whose <span data-x="concept-option-selectedness">selectedness</span> is true, if
+   any such <code>option</code> exists, otherwise null.</p></li>
 
    <li><p>If <var>option</var> is null, then run <span>clear a selectedoption</span> given
    <var>insertedNode</var>.</p></li>

From daabd988609e49fa674e9ad3e9dc0add8e96914c Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Mon, 4 Nov 2024 09:30:38 -0800
Subject: [PATCH 08/25] allow no selectedoption

---
 source | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/source b/source
index 9c7096948a6..399354aa60d 100644
--- a/source
+++ b/source
@@ -53000,8 +53000,8 @@ You cannot submit this form when the field is incorrect.</samp></pre>
    <dd><span>Phrasing content</span>, but there must be no <span>interactive content</span>
    descendant and no descendant with the <code data-x="attr-tabindex">tabindex</code> attribute
    specified.</dd>
-   <dd>If the element is the first child of a <code>select</code> element, then it must have one
-   <code>selectedoption</code> element.</dd>
+   <dd>If the element is the first child of a <code>select</code> element, then it may have zero or
+   one <code>selectedoption</code> element.</dd>
    <dt><span data-x="concept-element-attributes">Content attributes</span>:</dt>
    <dd><span>Global attributes</span></dd>
    <dd><code data-x="attr-fe-disabled">disabled</code></dd>
@@ -55913,9 +55913,9 @@ interface <dfn interface>HTMLSelectedOptionElement</dfn> : <span>HTMLElement</sp
 
   <p>The <code>selectedoption</code> element reflects the contents of a <code>select</code>
   element's currently selected <code>option</code> element. <code>selectedoption</code> elements can
-  be used to declaratively show the selected <code>option</code> element's contents in a different
-  part of the document, such as the <code>select</code> element's invoker button, with alternate
-  rendering based on different selectors in the author's stylesheet.</p>
+  be used to declaratively show the selected <code>option</code> element's contents within the
+  <code>select</code>'s <code>button</code>, with alternate rendering based on different selectors
+  in the author's stylesheet.</p>
 
   <p>Every time the selected <code>option</code> of a <code>select</code> switches from one option
   to another, or the currently selected <code>option</code>'s descendant DOM structure mutates, the

From 8863966f4d5d77c219ba17e891efd74f05b7da8d Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Mon, 4 Nov 2024 10:09:37 -0800
Subject: [PATCH 09/25] dont track mutations

---
 source | 62 +++++++++++++++++-----------------------------------------
 1 file changed, 18 insertions(+), 44 deletions(-)

diff --git a/source b/source
index 60438cb7cdc..5536b300add 100644
--- a/source
+++ b/source
@@ -1803,9 +1803,6 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
    <span>stack of open elements</span> of an <span>HTML parser</span>, then
    <span>process internal resource links</span> given <var>insertedNode</var>'s
    <span>node document</span>.</p></li>
-
-   <li><p>Run <span>maybe clone option into selectedoption</span> given
-   <var>insertedNode</var>.</p></li>
   </ol>
 
   <p>The <span data-x="concept-node-post-insert-ext">post-connection steps</span> for the HTML
@@ -1862,9 +1859,6 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
    <li><p>If <var>removedNode</var>'s <code data-x="attr-popover">popover</code> attribute is not in
    the <span data-x="attr-popover-none-state">no popover state</span>, then run the <span>hide
    popover algorithm</span> given <var>removedNode</var>, false, false, and false.</p></li>
-
-   <li><p>Run <span>maybe clone option into selectedoption</span> given
-   <var>oldParent</var>.</p></li>
   </ol>
 
   <p>A <dfn id="insert-an-element-into-a-document" data-x="node is inserted into a document"
@@ -54394,42 +54388,32 @@ interface <dfn interface>HTMLOptionElement</dfn> : <span>HTMLElement</span> {
    <li><p>Return null.</p></li>
   </ol>
 
-  <p>To <dfn>maybe clone option into selectedoption</dfn>, given an <code>Element</code>
-  <var>element</var>:</p>
+  <p>To <dfn>maybe clone an option into selectedoption</dfn>, given an <code>option</code>
+  <var>option</var>:</p>
 
   <ol>
    <li>
-    <p>For each <var>ancestor</var> of <var>element</var>'s <span
-    data-x="ancestor">ancestors</span>:</p>
-
-    <ol>
-     <li>
-      <p>If all of the following conditions are true:</p>
-
-      <ul>
-       <li><p><var>ancestor</var> is an <code>option</code> element;</p></li>
+    <p>If all of the following conditions are true:</p>
 
-       <li><p><var>ancestor</var> has a non-null <span>option element ancestor
-       select</span>;</p></li>
+    <ul>
+     <li><p><var>option</var> has a non-null <span>option element ancestor select</span>;</p></li>
 
-       <li><p><var>ancestor</var>'s <span>option element ancestor select</span> is rendered as a
-       <span>drop-down box</span>;</p></li>
+     <li><p><var>option</var>'s <span>option element ancestor select</span> does not have the <code
+     data-x="attr-select-multiple">multiple</code> attribute;</p></li>
 
-       <li><p><var>ancestor</var>'s <span data-x="concept-option-selectedness">selectedness</span>
-       is true,</p></li>
-      </ul>
+     <li><p><var>option</var>'s <span data-x="concept-option-selectedness">selectedness</span>
+     is true,</p></li>
+    </ul>
 
-      <p>then for each <var>selectedoption</var> of <var>ancestor</var>'s <span>option element
-      ancestor select</span>'s <span>select descendant selectedoption elements</span>, run
-      <span>clone an option into a selectedoption</span> given <var>ancestor</var> and
-      <var>selectedoption</var>.</p>
-     </li>
-    </ol>
+    <p>then for each <var>selectedoption</var> of <var>option</var>'s <span>option element
+    ancestor select</span>'s <span>select descendant selectedoption elements</span>, run
+    <span>clone an option into a selectedoption</span> given <var>option</var> and
+    <var>selectedoption</var>.</p>
    </li>
   </ol>
 
   <p>Whenever an <code>option</code> <var>option</var>'s <span
-  data-x="concept-option-selectedness">selectedness</span> is set to true, run <span>maybe clone
+  data-x="concept-option-selectedness">selectedness</span> is set to true, run <span>maybe clone an
   option into selectedoption</span> given <var>option</var>.</p>
 
   <dl class="domintro">
@@ -56125,10 +56109,9 @@ interface <dfn interface>HTMLSelectedOptionElement</dfn> : <span>HTMLElement</sp
   in the author's stylesheet.</p>
 
   <p>Every time the selected <code>option</code> of a <code>select</code> switches from one option
-  to another, or the currently selected <code>option</code>'s descendant DOM structure mutates, the
-  <code>selectedoption</code> element removes all of its children and replaces them with a new
-  cloned copy of the DOM structure of the <code>select</code>'s selected <code>option</code>
-  element.</p>
+  to another, the <code>selectedoption</code> element removes all of its children and replaces them
+  with a new cloned copy of the DOM structure of the <code>select</code>'s selected
+  <code>option</code> element.</p>
 
   <p><code>selectedoption</code> elements become associated with <code>select</code> elements when
   the <code>selectedoption</code> is a <span>descendant</span> of the <code>select</code>.</p>
@@ -56243,15 +56226,6 @@ interface <dfn interface>HTMLSelectedOptionElement</dfn> : <span>HTMLElement</sp
    </li>
   </ol>
 
-  <p>The following <span data-x="concept-element-attributes-change-ext">attribute change
-  steps</span>, given <var>element</var>, <var>localName</var>, <var>oldValue</var>,
-  <var>value</var>, and <var>namespace</var> are used for all <span>HTML elements</span> in order to
-  support <code>selectedoption</code> elements:</p>
-
-  <ol>
-   <li><p>Run <span>maybe clone option into selectedoption</span> given <var>element</var>.</p></li>
-  </ol>
-
 
 
   <h4 split-filename="form-control-infrastructure">Form control infrastructure</h4>

From 17ac232e7e49b552f626454bad960d3735cbeea2 Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Mon, 4 Nov 2024 10:15:45 -0800
Subject: [PATCH 10/25] rename to selectedcontent

---
 source | 86 +++++++++++++++++++++++++++++-----------------------------
 1 file changed, 43 insertions(+), 43 deletions(-)

diff --git a/source b/source
index 5536b300add..6cf74ba78a7 100644
--- a/source
+++ b/source
@@ -53202,7 +53202,7 @@ You cannot submit this form when the field is incorrect.</samp></pre>
    descendant and no descendant with the <code data-x="attr-tabindex">tabindex</code> attribute
    specified.</dd>
    <dd>If the element is the first child of a <code>select</code> element, then it may have zero or
-   one <code>selectedoption</code> element.</dd>
+   one <code>selectedcontent</code> element.</dd>
    <dt><span data-x="concept-element-attributes">Content attributes</span>:</dt>
    <dd><span>Global attributes</span></dd>
    <dd><code data-x="attr-fe-disabled">disabled</code></dd>
@@ -53516,8 +53516,8 @@ interface <dfn interface>HTMLSelectElement</dfn> : <span>HTMLElement</span> {
   element, and all the <code>option</code> element children of all the <code>optgroup</code> element
   children of the <code>select</code> element, in <span>tree order</span>.</p>
 
-  <p>Every <code>select</code> element has <dfn>select descendant selectedoption elements</dfn>,
-  which is a <span>list</span> of <code>selectedoption</code> elements, initially « ».</p>
+  <p>Every <code>select</code> element has <dfn>select descendant selectedcontent elements</dfn>,
+  which is a <span>list</span> of <code>selectedcontent</code> elements, initially « ».</p>
 
   <p>The <dfn element-attr for="select"><code data-x="attr-select-required">required</code></dfn>
   attribute is a <span>boolean attribute</span>. When specified, the user will be required to select
@@ -54388,7 +54388,7 @@ interface <dfn interface>HTMLOptionElement</dfn> : <span>HTMLElement</span> {
    <li><p>Return null.</p></li>
   </ol>
 
-  <p>To <dfn>maybe clone an option into selectedoption</dfn>, given an <code>option</code>
+  <p>To <dfn>maybe clone an option into selectedcontent</dfn>, given an <code>option</code>
   <var>option</var>:</p>
 
   <ol>
@@ -54405,16 +54405,16 @@ interface <dfn interface>HTMLOptionElement</dfn> : <span>HTMLElement</span> {
      is true,</p></li>
     </ul>
 
-    <p>then for each <var>selectedoption</var> of <var>option</var>'s <span>option element
-    ancestor select</span>'s <span>select descendant selectedoption elements</span>, run
-    <span>clone an option into a selectedoption</span> given <var>option</var> and
-    <var>selectedoption</var>.</p>
+    <p>then for each <var>selectedcontent</var> of <var>option</var>'s <span>option element
+    ancestor select</span>'s <span>select descendant selectedcontent elements</span>, run
+    <span>clone an option into a selectedcontent</span> given <var>option</var> and
+    <var>selectedcontent</var>.</p>
    </li>
   </ol>
 
   <p>Whenever an <code>option</code> <var>option</var>'s <span
   data-x="concept-option-selectedness">selectedness</span> is set to true, run <span>maybe clone an
-  option into selectedoption</span> given <var>option</var>.</p>
+  option into selectedcontent</span> given <var>option</var>.</p>
 
   <dl class="domintro">
    <dt><code data-x=""><var>option</var>.<span subdfn data-x="dom-option-selected">selected</span></code></dt>
@@ -56076,7 +56076,7 @@ interface <dfn interface>HTMLLegendElement</dfn> : <span>HTMLElement</span> {
 
   </div>
 
-  <h4>The <dfn element><code>selectedoption</code></dfn> element</h4>
+  <h4>The <dfn element><code>selectedcontent</code></dfn> element</h4>
 
   <dl class="element">
    <dt><span data-x="concept-element-categories">Categories</span>:</dt>
@@ -56090,34 +56090,34 @@ interface <dfn interface>HTMLLegendElement</dfn> : <span>HTMLElement</span> {
    <dd><span>Global attributes</span></dd>
    <dt><span
    data-x="concept-element-accessibility-considerations">Accessibility considerations</span>:</dt>
-   <dd><a href="https://w3c.github.io/html-aria/#el-selectedoption">For authors</a>.</dd>
-   <dd><a href="https://w3c.github.io/html-aam/#el-selectedoption">For implementers</a>.</dd>
+   <dd><a href="https://w3c.github.io/html-aria/#el-selectedcontent">For authors</a>.</dd>
+   <dd><a href="https://w3c.github.io/html-aam/#el-selectedcontent">For implementers</a>.</dd>
    <dt><span data-x="concept-element-dom">DOM interface</span>:</dt>
    <dd w-nodev>
     <pre><code class="idl">[Exposed=Window]
-interface <dfn interface>HTMLSelectedOptionElement</dfn> : <span>HTMLElement</span> {
+interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</span> {
   [<span>HTMLConstructor</span>] constructor();
 };</code></pre>
    </dd>
-   <dd w-dev>Uses <code>HTMLSelectedOptionElement</code>.</dd>
+   <dd w-dev>Uses <code>HTMLSelectedContentElement</code>.</dd>
   </dl>
 
-  <p>The <code>selectedoption</code> element reflects the contents of a <code>select</code>
-  element's currently selected <code>option</code> element. <code>selectedoption</code> elements can
+  <p>The <code>selectedcontent</code> element reflects the contents of a <code>select</code>
+  element's currently selected <code>option</code> element. <code>selectedcontent</code> elements can
   be used to declaratively show the selected <code>option</code> element's contents within the
   <code>select</code>'s <code>button</code>, with alternate rendering based on different selectors
   in the author's stylesheet.</p>
 
   <p>Every time the selected <code>option</code> of a <code>select</code> switches from one option
-  to another, the <code>selectedoption</code> element removes all of its children and replaces them
+  to another, the <code>selectedcontent</code> element removes all of its children and replaces them
   with a new cloned copy of the DOM structure of the <code>select</code>'s selected
   <code>option</code> element.</p>
 
-  <p><code>selectedoption</code> elements become associated with <code>select</code> elements when
-  the <code>selectedoption</code> is a <span>descendant</span> of the <code>select</code>.</p>
+  <p><code>selectedcontent</code> elements become associated with <code>select</code> elements when
+  the <code>selectedcontent</code> is a <span>descendant</span> of the <code>select</code>.</p>
 
-  <p>To <dfn>clone an option into a selectedoption</dfn>, given an <code>option</code> element
-  <var>option</var> and a <code>selectedoption</code> element <var>selectedOption</var>:</p>
+  <p>To <dfn>clone an option into a selectedcontent</dfn>, given an <code>option</code> element
+  <var>option</var> and a <code>selectedcontent</code> element <var>selectedcontent</var>:</p>
 
   <ol>
    <li><p>Let <var>nodes</var> be « ».</p></li>
@@ -56139,28 +56139,28 @@ interface <dfn interface>HTMLSelectedOptionElement</dfn> : <span>HTMLElement</sp
    <var>nodes</var> and <var>option</var>'s <span>node document</span>.</p></li>
 
    <li><p><span>Ensure pre-insertion validity</span> of <var>convertedNode</var> into
-   <var>selectedOption</var> before null.</p></li>
+   <var>SelectedContent</var> before null.</p></li>
 
    <li><p><span data-x="concept-node-replace-all">Replace all</span> with <var>convertedNode</var>
-   within <var>selectedOption</var>.</p></li>
+   within <var>selectedcontent</var>.</p></li>
   </ol>
 
-  <p>To <dfn>clear a selectedoption</dfn> given a <code>selectedoption</code> element
-  <var>selectedoption</var>:</p>
+  <p>To <dfn>clear a selectedcontent</dfn> given a <code>selectedcontent</code> element
+  <var>selectedcontent</var>:</p>
 
   <ol>
    <li><p><span data-x="concept-node-remove-ext">Remove</span> all <span
-   data-x="concept-tree-child">children</span> of <var>selectedoption</var>, in <span>tree
+   data-x="concept-tree-child">children</span> of <var>selectedcontent</var>, in <span>tree
    order</span></p></li>
   </ol>
 
-  <p>The <code>selectedoption</code> <span>HTML element insertion steps</span>, given
-  <var>selectedoption</var>, are:</p>
+  <p>The <code>selectedcontent</code> <span>HTML element insertion steps</span>, given
+  <var>selectedcontent</var>, are:</p>
 
   <ol>
    <li><p>Let <var>nearestSelectAncestor</var> be null.</p></li>
 
-   <li><p>Let <var>ancestor</var> be <var>selectedoption</var>'s <span>parent</span>.</p></li>
+   <li><p>Let <var>ancestor</var> be <var>selectedcontent</var>'s <span>parent</span>.</p></li>
 
    <li>
     <p><span>While</span> <var>nearestSelectAncestor</var> is null and <var>ancestor</var> is not
@@ -56176,8 +56176,8 @@ interface <dfn interface>HTMLSelectedOptionElement</dfn> : <span>HTMLElement</sp
 
    <li><p>If <var>nearestSelectAncestor</var> is null, then return.</p></li>
 
-   <li><p><span data-x="list append">Append</span> <var>selectedoption</var> to
-   <var>nearestSelectAncestor</var>'s <span>select descendant selectedoption
+   <li><p><span data-x="list append">Append</span> <var>selectedcontent</var> to
+   <var>nearestSelectAncestor</var>'s <span>select descendant selectedcontent
    elements</span>.</p></li>
 
    <li><p>Let <var>option</var> be the first <code>option</code> in
@@ -56185,19 +56185,19 @@ interface <dfn interface>HTMLSelectedOptionElement</dfn> : <span>HTMLElement</sp
    options</span> whose <span data-x="concept-option-selectedness">selectedness</span> is true, if
    any such <code>option</code> exists, otherwise null.</p></li>
 
-   <li><p>If <var>option</var> is null, then run <span>clear a selectedoption</span> given
+   <li><p>If <var>option</var> is null, then run <span>clear a selectedcontent</span> given
    <var>insertedNode</var>.</p></li>
 
-   <li><p>Otherwise, run <span>clone an option into a selectedoption</span> given <var>option</var>
+   <li><p>Otherwise, run <span>clone an option into a selectedcontent</span> given <var>option</var>
    and <var>insertedNode</var>.</p></li>
   </ol>
 
-  <p>The <code>selectedoption</code> <span>HTML element removing steps</span>, given
-  <var>selectedoption</var> and <var>oldParent</var>, are:</p>
+  <p>The <code>selectedcontent</code> <span>HTML element removing steps</span>, given
+  <var>selectedcontent</var> and <var>oldParent</var>, are:</p>
 
   <ol>
    <li>
-    <p>For each <var>ancestor</var> of <var>selectedoption</var>'s <span
+    <p>For each <var>ancestor</var> of <var>selectedcontent</var>'s <span
     data-x="ancestor">ancestors</span>:</p>
 
     <ol>
@@ -56214,10 +56214,10 @@ interface <dfn interface>HTMLSelectedOptionElement</dfn> : <span>HTMLElement</sp
       <p>If <var>ancestor</var> is a <code>select</code> element, then:</p>
 
       <ol>
-       <li><p><span data-x="list remove">remove</span> <var>selectedoption</var> from
-       <var>ancestor</var>'s <span>select descendant selectedoption elements</span>.</p></li>
+       <li><p><span data-x="list remove">remove</span> <var>selectedcontent</var> from
+       <var>ancestor</var>'s <span>select descendant selectedcontent elements</span>.</p></li>
 
-       <li><p>Run <span>clear a selectedoption</span> given <var>selectedoption</var>.</p></li>
+       <li><p>Run <span>clear a selectedcontent</span> given <var>selectedcontent</var>.</p></li>
 
        <li><p>Return.</p></li>
       </ol>
@@ -140691,13 +140691,13 @@ interface <dfn interface>External</dfn> {
     </tr>
 
     <tr>
-     <th><code>selectedoption</code></th>
+     <th><code>selectedcontent</code></th>
      <td>Mirrors content from an <code>option</code></td>
      <td>none</td>
      <td><code>button</code></td>
      <td>empty</td>
      <td><span data-x="global attributes">globals</span></td>
-     <td><code>HTMLSelectedOptionElement</code></td>
+     <td><code>HTMLSelectedContentElement</code></td>
     </tr>
 
     <tr>
@@ -143493,8 +143493,8 @@ interface <dfn interface>External</dfn> {
      <td> <code>HTMLSelectElement</code> : <code>HTMLElement</code>
 
     <tr>
-     <td> <code>selectedoption</code>
-     <td> <code>HTMLSelectedOptionelement</code> : <code>HTMLElement</code>
+     <td> <code>selectedcontent</code>
+     <td> <code>HTMLSelectedContentElement</code> : <code>HTMLElement</code>
 
     <tr>
      <td> <code>slot</code>

From 4960a7707e8458f7e4cea5624d8a4353ee7325db Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Mon, 4 Nov 2024 10:23:21 -0800
Subject: [PATCH 11/25] add parser cloning

---
 source | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/source b/source
index 6cf74ba78a7..a11242eab83 100644
--- a/source
+++ b/source
@@ -131626,9 +131626,18 @@ document.body.appendChild(text);
 
    <dt>An end tag whose tag name is "option"</dt>
    <dd>
-    <p>If the <span>current node</span> is an <code>option</code> element, then pop that node from
-    the <span>stack of open elements</span>. Otherwise, this is a <span>parse error</span>; ignore
-    the token.</p>
+    <p>If the <span>current node</span> is an <code>option</code> element, then:</p>
+
+    <ol>
+     <li><p>Let <var>option</var> be the <span>current node</span>.</p></li>
+
+     <li><p>Pop <var>option</var> from the <span>stack of open elements</span>.</p></li>
+
+     <li><p>Run <span>maybe clone an option into selectedcontent</span> given
+     <var>option</var>.</p></li>
+    </ol>
+
+    <p>Otherwise, this is a <span>parse error</span>; ignore the token.</p>
    </dd>
 
    <dt>An end tag whose tag name is "select"</dt>

From 10d1a147141047a84a2397c72ab06c1c2352cab1 Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Mon, 11 Nov 2024 11:59:34 -0800
Subject: [PATCH 12/25] improve things

---
 source | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/source b/source
index a11242eab83..e1caf13c73a 100644
--- a/source
+++ b/source
@@ -53201,8 +53201,8 @@ You cannot submit this form when the field is incorrect.</samp></pre>
    <dd><span>Phrasing content</span>, but there must be no <span>interactive content</span>
    descendant and no descendant with the <code data-x="attr-tabindex">tabindex</code> attribute
    specified.</dd>
-   <dd>If the element is the first child of a <code>select</code> element, then it may have zero or
-   one <code>selectedcontent</code> element.</dd>
+   <dd>If the element is the first child of a <code>select</code> element, then it may also have
+   zero or one <code>selectedcontent</code> element.</dd>
    <dt><span data-x="concept-element-attributes">Content attributes</span>:</dt>
    <dd><span>Global attributes</span></dd>
    <dd><code data-x="attr-fe-disabled">disabled</code></dd>
@@ -53516,8 +53516,9 @@ interface <dfn interface>HTMLSelectElement</dfn> : <span>HTMLElement</span> {
   element, and all the <code>option</code> element children of all the <code>optgroup</code> element
   children of the <code>select</code> element, in <span>tree order</span>.</p>
 
-  <p>Every <code>select</code> element has <dfn>select descendant selectedcontent elements</dfn>,
-  which is a <span>list</span> of <code>selectedcontent</code> elements, initially « ».</p>
+  <p>Every <code>select</code> element has <dfn>descendant <code>selectedcontent</code>
+  elements</dfn>, which is a <span>list</span> of <code>selectedcontent</code> elements, initially
+  « ».</p>
 
   <p>The <dfn element-attr for="select"><code data-x="attr-select-required">required</code></dfn>
   attribute is a <span>boolean attribute</span>. When specified, the user will be required to select
@@ -53670,6 +53671,18 @@ interface <dfn interface>HTMLSelectElement</dfn> : <span>HTMLElement</span> {
   <ol>
    <li>Set the <code>select</code> element's <span>user validity</span> to true.</li>
 
+   <li><p>Let <var>option</var> be the first element in the <code>select</code>'s <span
+   data-x="concept-select-option-list">list of options</span> which has its <span
+   data-x="concept-option-selectedness">selectedness</span> set to true if any such
+   <code>option</code> exists, otherwise null.</p></li>
+
+   <li><p>If <var>option</var> is null, then for each <var>selectedcontent</var> of the
+   <code>select</code>'s <span>descendant <code>selectedcontent</code> elements</span>, run
+   <span>clear a selectedcontent</span> given <var>selectedcontent</var>.</p></li>
+
+   <li><p>Otherwise, run <span>maybe clone an option into selectedcontent</span> given
+   <var>option</var>.</p></li>
+
    <li><p><span data-x="concept-event-fire">Fire an event</span> named <code
    data-x="event-input">input</code> at the <code>select</code> element, with the <code
    data-x="dom-Event-bubbles">bubbles</code> and <code data-x="dom-Event-composed">composed</code>
@@ -54406,16 +54419,12 @@ interface <dfn interface>HTMLOptionElement</dfn> : <span>HTMLElement</span> {
     </ul>
 
     <p>then for each <var>selectedcontent</var> of <var>option</var>'s <span>option element
-    ancestor select</span>'s <span>select descendant selectedcontent elements</span>, run
+    ancestor select</span>'s <span>descendant <code>selectedcontent</code> elements</span>, run
     <span>clone an option into a selectedcontent</span> given <var>option</var> and
     <var>selectedcontent</var>.</p>
    </li>
   </ol>
 
-  <p>Whenever an <code>option</code> <var>option</var>'s <span
-  data-x="concept-option-selectedness">selectedness</span> is set to true, run <span>maybe clone an
-  option into selectedcontent</span> given <var>option</var>.</p>
-
   <dl class="domintro">
    <dt><code data-x=""><var>option</var>.<span subdfn data-x="dom-option-selected">selected</span></code></dt>
 
@@ -56177,7 +56186,7 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
    <li><p>If <var>nearestSelectAncestor</var> is null, then return.</p></li>
 
    <li><p><span data-x="list append">Append</span> <var>selectedcontent</var> to
-   <var>nearestSelectAncestor</var>'s <span>select descendant selectedcontent
+   <var>nearestSelectAncestor</var>'s <span>descendant <code>selectedcontent</code>
    elements</span>.</p></li>
 
    <li><p>Let <var>option</var> be the first <code>option</code> in
@@ -56215,7 +56224,7 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
 
       <ol>
        <li><p><span data-x="list remove">remove</span> <var>selectedcontent</var> from
-       <var>ancestor</var>'s <span>select descendant selectedcontent elements</span>.</p></li>
+       <var>ancestor</var>'s <span>descendant <code>selectedcontent</code> elements</span>.</p></li>
 
        <li><p>Run <span>clear a selectedcontent</span> given <var>selectedcontent</var>.</p></li>
 

From 1ee134d36e2c031647eb235d029eb0cf874f9aa5 Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Fri, 22 Nov 2024 12:43:51 -0800
Subject: [PATCH 13/25] only update first inserted selectedoption

---
 source | 62 +++++++++++++++++++++++++++++++++++-----------------------
 1 file changed, 38 insertions(+), 24 deletions(-)

diff --git a/source b/source
index e1caf13c73a..8070a797ae3 100644
--- a/source
+++ b/source
@@ -53200,9 +53200,8 @@ You cannot submit this form when the field is incorrect.</samp></pre>
    <dt><span data-x="concept-element-content-model">Content model</span>:</dt>
    <dd><span>Phrasing content</span>, but there must be no <span>interactive content</span>
    descendant and no descendant with the <code data-x="attr-tabindex">tabindex</code> attribute
-   specified.</dd>
-   <dd>If the element is the first child of a <code>select</code> element, then it may also have
-   zero or one <code>selectedcontent</code> element.</dd>
+   specified. If the element is the first child of a <code>select</code> element, then it may also
+   have zero or one <code>selectedcontent</code> element.</dd>
    <dt><span data-x="concept-element-attributes">Content attributes</span>:</dt>
    <dd><span>Global attributes</span></dd>
    <dd><code data-x="attr-fe-disabled">disabled</code></dd>
@@ -53676,12 +53675,13 @@ interface <dfn interface>HTMLSelectElement</dfn> : <span>HTMLElement</span> {
    data-x="concept-option-selectedness">selectedness</span> set to true if any such
    <code>option</code> exists, otherwise null.</p></li>
 
-   <li><p>If <var>option</var> is null, then for each <var>selectedcontent</var> of the
-   <code>select</code>'s <span>descendant <code>selectedcontent</code> elements</span>, run
-   <span>clear a selectedcontent</span> given <var>selectedcontent</var>.</p></li>
+   <li><p>If <var>option</var> is not null, then run <span>maybe clone an option into
+   selectedcontent</span> given <var>option</var>.</p></li>
 
-   <li><p>Otherwise, run <span>maybe clone an option into selectedcontent</span> given
-   <var>option</var>.</p></li>
+   <li><p>Otherwise, if <code>select</code>'s <span>descendant <code>selectedcontent</code>
+   elements</span> is not empty, then run <span>clear a selectedcontent</span> given the first
+   element in <code>select</code>'s <span>descendant <code>selectedcontent</code>
+   elements</span>.</p></li>
 
    <li><p><span data-x="concept-event-fire">Fire an event</span> named <code
    data-x="event-input">input</code> at the <code>select</code> element, with the <code
@@ -54390,7 +54390,7 @@ interface <dfn interface>HTMLOptionElement</dfn> : <span>HTMLElement</span> {
   <ol>
    <li>
     <p>For each <var>ancestor</var> of <var>option</var>'s <span
-    data-x="ancestor">ancestors</span>:</p>
+    data-x="ancestor">ancestors</span> in reverse <span>tree order</span>:</p>
 
     <ol>
      <li><p>If <var>ancestor</var> is a <code>select</code>, then return
@@ -54416,12 +54416,14 @@ interface <dfn interface>HTMLOptionElement</dfn> : <span>HTMLElement</span> {
 
      <li><p><var>option</var>'s <span data-x="concept-option-selectedness">selectedness</span>
      is true,</p></li>
+
+     <li><p><var>option</var>'s <span>option element ancestor select</span>'s <span>descendant
+     <code>selectedcontent</code> elements</span> is not empty,</p></li>
     </ul>
 
-    <p>then for each <var>selectedcontent</var> of <var>option</var>'s <span>option element
-    ancestor select</span>'s <span>descendant <code>selectedcontent</code> elements</span>, run
-    <span>clone an option into a selectedcontent</span> given <var>option</var> and
-    <var>selectedcontent</var>.</p>
+    <p>then run <span>clone an option into a selectedcontent</span> given <var>option</var> and the
+    first element of <var>option</var>'s <span>option element ancestor select</span>'s
+    <span>descendant <code>selectedcontent</code> elements</span>.</p>
    </li>
   </ol>
 
@@ -56189,16 +56191,23 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
    <var>nearestSelectAncestor</var>'s <span>descendant <code>selectedcontent</code>
    elements</span>.</p></li>
 
-   <li><p>Let <var>option</var> be the first <code>option</code> in
-   <var>nearestSelectAncestor</var>'s <span data-x="concept-select-option-list">list of
-   options</span> whose <span data-x="concept-option-selectedness">selectedness</span> is true, if
-   any such <code>option</code> exists, otherwise null.</p></li>
+   <li>
+    <p>If <var>selectedcontent</var> is the first item in <var>nearestAncestorSelect</var>'s
+    <span>descendant <code>selectedcontent</code> elements</span>, then:</p>
 
-   <li><p>If <var>option</var> is null, then run <span>clear a selectedcontent</span> given
-   <var>insertedNode</var>.</p></li>
+    <ol>
+     <li><p>Let <var>option</var> be the first <code>option</code> in
+     <var>nearestSelectAncestor</var>'s <span data-x="concept-select-option-list">list of
+     options</span> whose <span data-x="concept-option-selectedness">selectedness</span> is true, if
+     any such <code>option</code> exists, otherwise null.</p></li>
 
-   <li><p>Otherwise, run <span>clone an option into a selectedcontent</span> given <var>option</var>
-   and <var>insertedNode</var>.</p></li>
+     <li><p>If <var>option</var> is null, then run <span>clear a selectedcontent</span> given
+     <var>insertedNode</var>.</p></li>
+
+     <li><p>Otherwise, run <span>clone an option into a selectedcontent</span> given
+     <var>option</var> and <var>insertedNode</var>.</p></li>
+    </ol>
+   </li>
   </ol>
 
   <p>The <code>selectedcontent</code> <span>HTML element removing steps</span>, given
@@ -56207,7 +56216,7 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
   <ol>
    <li>
     <p>For each <var>ancestor</var> of <var>selectedcontent</var>'s <span
-    data-x="ancestor">ancestors</span>:</p>
+    data-x="ancestor">ancestors</span> in reverse <span>tree order</span>:</p>
 
     <ol>
      <li><p>If <var>ancestor</var> is a <code>select</code> element, then return.</p></li>
@@ -56216,17 +56225,22 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
 
    <li>
     <p>For each <var>ancestor</var> of <var>oldParent</var>'s <span data-x="inclusive
-    ancestor">inclusive ancestors</span>:</p>
+    ancestor">inclusive ancestors</span> in reverse <span>tree order</span>:</p>
 
     <ol>
      <li>
       <p>If <var>ancestor</var> is a <code>select</code> element, then:</p>
 
       <ol>
+       <li><p>Let <var>wasFirst</var> be true if <var>selectedcontent</var> is the first element in
+       <var>ancestor</var>'s <span>descendant <code>selectedcontent</code> elements</span>,
+       otherwise false.</p></li>
+
        <li><p><span data-x="list remove">remove</span> <var>selectedcontent</var> from
        <var>ancestor</var>'s <span>descendant <code>selectedcontent</code> elements</span>.</p></li>
 
-       <li><p>Run <span>clear a selectedcontent</span> given <var>selectedcontent</var>.</p></li>
+       <li><p>If <var>wasFirst</var> is true, then run <span>clear a selectedcontent</span> given
+       <var>selectedcontent</var>.</p></li>
 
        <li><p>Return.</p></li>
       </ol>

From ec5244b53b8cac623682c9ae7686dc0d7fdd36eb Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Fri, 22 Nov 2024 13:15:05 -0800
Subject: [PATCH 14/25] some nits

---
 source | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/source b/source
index 8070a797ae3..bb7fbcf087d 100644
--- a/source
+++ b/source
@@ -56116,16 +56116,16 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
   <p>The <code>selectedcontent</code> element reflects the contents of a <code>select</code>
   element's currently selected <code>option</code> element. <code>selectedcontent</code> elements can
   be used to declaratively show the selected <code>option</code> element's contents within the
-  <code>select</code>'s <code>button</code>, with alternate rendering based on different selectors
-  in the author's stylesheet.</p>
+  <code>select</code> element's <code>button</code> element.</p>
 
-  <p>Every time the selected <code>option</code> of a <code>select</code> switches from one option
-  to another, the <code>selectedcontent</code> element removes all of its children and replaces them
-  with a new cloned copy of the DOM structure of the <code>select</code>'s selected
+  <p w-dev>Every time the selected <code>option</code> of a <code>select</code> switches from one
+  option to another, the <code>selectedcontent</code> element removes all of its children and
+  replaces them with a new cloned copy of the DOM structure of the <code>select</code>'s selected
   <code>option</code> element.</p>
 
-  <p><code>selectedcontent</code> elements become associated with <code>select</code> elements when
-  the <code>selectedcontent</code> is a <span>descendant</span> of the <code>select</code>.</p>
+  <p><code>selectedcontent</code> elements become associated with a <code>select</code> element when
+  the <code>selectedcontent</code> is a <span>descendant</span> of the <code>select</code>'s first
+  child <code>button</code>.</p>
 
   <p>To <dfn>clone an option into a selectedcontent</dfn>, given an <code>option</code> element
   <var>option</var> and a <code>selectedcontent</code> element <var>selectedcontent</var>:</p>

From 9463f7e1a81c78bca06a1c4db1e95be0155bd93c Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Fri, 22 Nov 2024 13:22:35 -0800
Subject: [PATCH 15/25] improve name of option element ancestor select

---
 source | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/source b/source
index bb7fbcf087d..56797885129 100644
--- a/source
+++ b/source
@@ -54384,8 +54384,8 @@ interface <dfn interface>HTMLOptionElement</dfn> : <span>HTMLElement</span> {
 
   </div>
 
-  <p>To get the <dfn>option element ancestor select</dfn> given an <code>option</code>
-  <var>option</var>:</p>
+  <p>To get the <dfn><code>option</code> element nearest ancestor <code>select</code></dfn> given an
+  <code>option</code> <var>option</var>:</p>
 
   <ol>
    <li>
@@ -54409,21 +54409,24 @@ interface <dfn interface>HTMLOptionElement</dfn> : <span>HTMLElement</span> {
     <p>If all of the following conditions are true:</p>
 
     <ul>
-     <li><p><var>option</var> has a non-null <span>option element ancestor select</span>;</p></li>
+     <li><p><var>option</var> has a non-null <span><code>option</code> element nearest ancestor
+     <code>select</code></span>;</p></li>
 
-     <li><p><var>option</var>'s <span>option element ancestor select</span> does not have the <code
+     <li><p><var>option</var>'s <span><code>option</code> element nearest ancestor
+     <code>select</code></span> does not have the <code
      data-x="attr-select-multiple">multiple</code> attribute;</p></li>
 
      <li><p><var>option</var>'s <span data-x="concept-option-selectedness">selectedness</span>
      is true,</p></li>
 
-     <li><p><var>option</var>'s <span>option element ancestor select</span>'s <span>descendant
-     <code>selectedcontent</code> elements</span> is not empty,</p></li>
+     <li><p><var>option</var>'s <span><code>option</code> element nearest ancestor
+     <code>select</code></span>'s <span>descendant <code>selectedcontent</code> elements</span> is
+     not empty,</p></li>
     </ul>
 
     <p>then run <span>clone an option into a selectedcontent</span> given <var>option</var> and the
-    first element of <var>option</var>'s <span>option element ancestor select</span>'s
-    <span>descendant <code>selectedcontent</code> elements</span>.</p>
+    first element of <var>option</var>'s <span><code>option</code> element nearest ancestor
+    <code>select</code></span>'s <span>descendant <code>selectedcontent</code> elements</span>.</p>
    </li>
   </ol>
 

From 02b8cde798bae7ac26d5f2e9288c5146478151ce Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Fri, 22 Nov 2024 13:32:58 -0800
Subject: [PATCH 16/25] more nits

---
 source | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/source b/source
index 56797885129..bea82741a78 100644
--- a/source
+++ b/source
@@ -56149,14 +56149,14 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
     </ol>
    </li>
 
-   <li><p>Let <var>convertedNode</var> be the result of <span>convert nodes into a node</span> given
-   <var>nodes</var> and <var>option</var>'s <span>node document</span>.</p></li>
+   <li><p>Let <var>documentFragment</var> be the result of running <span>convert nodes into a
+   node</span> given <var>nodes</var> and <var>option</var>'s <span>node document</span>.</p></li>
 
-   <li><p><span>Ensure pre-insertion validity</span> of <var>convertedNode</var> into
-   <var>SelectedContent</var> before null.</p></li>
+   <li><p><span>Ensure pre-insertion validity</span> of <var>documentFragment</var> into
+   <var>selectedContent</var> before null.</p></li>
 
-   <li><p><span data-x="concept-node-replace-all">Replace all</span> with <var>convertedNode</var>
-   within <var>selectedcontent</var>.</p></li>
+   <li><p><span data-x="concept-node-replace-all">Replace all</span> with
+   <var>documentFragment</var> within <var>selectedcontent</var>.</p></li>
   </ol>
 
   <p>To <dfn>clear a selectedcontent</dfn> given a <code>selectedcontent</code> element
@@ -56165,7 +56165,7 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
   <ol>
    <li><p><span data-x="concept-node-remove-ext">Remove</span> all <span
    data-x="concept-tree-child">children</span> of <var>selectedcontent</var>, in <span>tree
-   order</span></p></li>
+   order</span>.</p></li>
   </ol>
 
   <p>The <code>selectedcontent</code> <span>HTML element insertion steps</span>, given

From e268b44949cad9d2e5a5829b287d9ea5ac617aa4 Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Tue, 3 Dec 2024 13:14:15 -0800
Subject: [PATCH 17/25] use post-connection steps

---
 source | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/source b/source
index bea82741a78..3806c262d1a 100644
--- a/source
+++ b/source
@@ -56168,7 +56168,7 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
    order</span>.</p></li>
   </ol>
 
-  <p>The <code>selectedcontent</code> <span>HTML element insertion steps</span>, given
+  <p>The <code>selectedcontent</code> <span>HTML element post-connection steps</span>, given
   <var>selectedcontent</var>, are:</p>
 
   <ol>

From f0984d34613e284dfb6eb8c7d04f82f2e696041c Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Mon, 9 Dec 2024 15:42:58 -0800
Subject: [PATCH 18/25] Add disabled concept

---
 source | 52 +++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 37 insertions(+), 15 deletions(-)

diff --git a/source b/source
index 79d87557179..408e005fd76 100644
--- a/source
+++ b/source
@@ -54596,23 +54596,26 @@ interface <dfn interface>HTMLOptionElement</dfn> : <span>HTMLElement</span> {
   <var>option</var>:</p>
 
   <ol>
+   <li><p>Let <var>select</var> be <var>option</var>'s <span><code>option</code> element nearest
+   ancestor <code>select</code></span>.</p></li>
+
    <li>
     <p>If all of the following conditions are true:</p>
 
     <ul>
-     <li><p><var>option</var> has a non-null <span><code>option</code> element nearest ancestor
-     <code>select</code></span>;</p></li>
+     <li><p><var>select</var> is not null;</p></li>
 
-     <li><p><var>option</var>'s <span><code>option</code> element nearest ancestor
-     <code>select</code></span> does not have the <code
-     data-x="attr-select-multiple">multiple</code> attribute;</p></li>
+     <li><p><var>select</var> does not have the <code data-x="attr-select-multiple">multiple</code>
+     attribute;</p></li>
 
      <li><p><var>option</var>'s <span data-x="concept-option-selectedness">selectedness</span>
-     is true,</p></li>
+     is true;</p></li>
+
+     <li><p><var>select</var>'s <span>descendant <code>selectedcontent</code> elements</span> is not
+     empty;</p></li>
 
-     <li><p><var>option</var>'s <span><code>option</code> element nearest ancestor
-     <code>select</code></span>'s <span>descendant <code>selectedcontent</code> elements</span> is
-     not empty,</p></li>
+     <li><p>The first element in <var>select</var>'s <span>descendant <code>selectedcontent</code>
+     elements</span> is not <span data-x="selectedcontent-disabled">disabled</span>,</p></li>
     </ul>
 
     <p>then run <span>clone an option into a selectedcontent</span> given <var>option</var> and the
@@ -56321,6 +56324,10 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
   the <code>selectedcontent</code> is a <span>descendant</span> of the <code>select</code>'s first
   child <code>button</code>.</p>
 
+  <p>Every <code>selectedcontent</code> element has a <dfn
+  data-x="selectedcontent-disabled">disabled</dfn> state, which is a boolean, initially set to
+  false.</p>
+
   <p>To <dfn>clone an option into a selectedcontent</dfn>, given an <code>option</code> element
   <var>option</var> and a <code>selectedcontent</code> element <var>selectedcontent</var>:</p>
 
@@ -56367,15 +56374,29 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
 
    <li><p>Let <var>ancestor</var> be <var>selectedcontent</var>'s <span>parent</span>.</p></li>
 
+   <li><p>Set <var>selectedcontent</var>'s <span data-x="selectedcontent-disabled">disabled</span>
+   state to false.</p></li>
+
    <li>
-    <p><span>While</span> <var>nearestSelectAncestor</var> is null and <var>ancestor</var> is not
-    null:</p>
+    <p>For each <var>ancestor</var> of <var>selectedcontent</var>'s <span
+    data-x="ancestor">ancestors</span> in reverse <span>tree order</span>:</p>
 
     <ol>
-     <li><p>If <var>ancestor</var> is a <code>select</code> element, then set
-     <var>nearestSelectAncestor</var> to <var>ancestor</var>.</p></li>
+     <li>
+      <p>If <var>ancestor</var> is a <code>select</code> element, then:</p>
+
+      <ol>
+       <li><p>If <var>nearestAncestorSelect</var> is null, then set <var>nearestAncestorSelect</var>
+       to <var>select</var>.</p></li>
+
+       <li><p>Otherwise, set <var>selectedcontent</var>'s <span
+       data-x="selectedcontent-disabled">disabled</span> state to true.</p></li>
+      </ol>
+     </li>
 
-     <li><p>Set <var>ancestor</var> to <var>ancestor</var>'s <span>parent</span>.</p></li>
+     <li><p>If <var>ancestor</var> is an <code>option</code> element or a
+     <code>selectedcontent</code> element, then set <var>selectedcontent</var>'s <span
+     data-x="selectedcontent-disabled">disabled</span> state to true.</p></li>
     </ol>
    </li>
 
@@ -56386,7 +56407,8 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
    elements</span>.</p></li>
 
    <li>
-    <p>If <var>selectedcontent</var> is the first item in <var>nearestAncestorSelect</var>'s
+    <p>If <var>selectedcontent</var> is not <span data-x="selectedcontent-disabled">disabled</span>
+    and <var>selectedcontent</var> is the first item in <var>nearestAncestorSelect</var>'s
     <span>descendant <code>selectedcontent</code> elements</span>, then:</p>
 
     <ol>

From d8a05e5a4601555cb38ca8658f64d9accabdf158 Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Wed, 11 Dec 2024 09:57:37 -0800
Subject: [PATCH 19/25] Make value and selectedIndex setters trigger cloning

---
 source | 143 +++++++++++++++++++++++++++++++++++----------------------
 1 file changed, 87 insertions(+), 56 deletions(-)

diff --git a/source b/source
index 408e005fd76..36d88095e4e 100644
--- a/source
+++ b/source
@@ -53861,18 +53861,8 @@ interface <dfn interface>HTMLSelectElement</dfn> : <span>HTMLElement</span> {
   <ol>
    <li>Set the <code>select</code> element's <span>user validity</span> to true.</li>
 
-   <li><p>Let <var>option</var> be the first element in the <code>select</code>'s <span
-   data-x="concept-select-option-list">list of options</span> which has its <span
-   data-x="concept-option-selectedness">selectedness</span> set to true if any such
-   <code>option</code> exists, otherwise null.</p></li>
-
-   <li><p>If <var>option</var> is not null, then run <span>maybe clone an option into
-   selectedcontent</span> given <var>option</var>.</p></li>
-
-   <li><p>Otherwise, if <code>select</code>'s <span>descendant <code>selectedcontent</code>
-   elements</span> is not empty, then run <span>clear a selectedcontent</span> given the first
-   element in <code>select</code>'s <span>descendant <code>selectedcontent</code>
-   elements</span>.</p></li>
+   <li><p>Run <span>update a <code>select</code>'s <code>selectedcontent</code></span> given the
+   <code>select</code> element.</p></li>
 
    <li><p><span data-x="concept-event-fire">Fire an event</span> named <code
    data-x="event-input">input</code> at the <code>select</code> element, with the <code
@@ -54091,13 +54081,22 @@ interface <dfn interface>HTMLSelectElement</dfn> : <span>HTMLElement</span> {
   order</span> that has its <span data-x="concept-option-selectedness">selectedness</span> set to
   true, if any. If there isn't one, then it must return &#x2212;1.</p>
 
-  <p>On setting, the <code data-x="dom-select-selectedIndex">selectedIndex</code> attribute must set
-  the <span data-x="concept-option-selectedness">selectedness</span> of all the <code>option</code>
-  elements in the <span data-x="concept-select-option-list">list of options</span> to false, and
-  then the <code>option</code> element in the <span data-x="concept-select-option-list">list of
-  options</span> whose <span data-x="concept-option-index">index</span> is the given new value, if
-  any, must have its <span data-x="concept-option-selectedness">selectedness</span> set to true and
-  its <span data-x="concept-option-dirtiness">dirtiness</span> set to true.</p>
+  <p>On setting, the <code data-x="dom-select-selectedIndex">selectedIndex</code> attribute must run
+  the following steps:</p>
+
+  <ol>
+   <li><p>Set the <span data-x="concept-option-selectedness">selectedness</span> of all the
+   <code>option</code> elements in the <span data-x="concept-select-option-list">list of
+   options</span> to false.</p></li>
+
+   <li><p>The <code>option</code> element in the <span data-x="concept-select-option-list">list of
+   options</span> whose <span data-x="concept-option-index">index</span> is the given new value, if
+   any, must have its <span data-x="concept-option-selectedness">selectedness</span> set to true and
+   its <span data-x="concept-option-dirtiness">dirtiness</span> set to true.</p></li>
+
+   <li><p>Run <span>update a <code>select</code>'s <code>selectedcontent</code></span> given this
+   <code>select</code>.</p></li>
+  </ol>
 
   <p class="note">This can result in no element having a <span
   data-x="concept-option-selectedness">selectedness</span> set to true even in the case of the
@@ -54111,14 +54110,23 @@ interface <dfn interface>HTMLSelectElement</dfn> : <span>HTMLElement</span> {
   data-x="concept-option-selectedness">selectedness</span> set to true, if any. If there isn't one,
   then it must return the empty string.</p>
 
-  <p>On setting, the <code data-x="dom-select-value">value</code> attribute must set the <span
-  data-x="concept-option-selectedness">selectedness</span> of all the <code>option</code> elements
-  in the <span data-x="concept-select-option-list">list of options</span> to false, and then the
-  first <code>option</code> element in the <span data-x="concept-select-option-list">list of
-  options</span>, in <span>tree order</span>, whose <span data-x="concept-option-value">value</span>
-  is equal to the given new value, if any, must have its <span
-  data-x="concept-option-selectedness">selectedness</span> set to true and its <span
-  data-x="concept-option-dirtiness">dirtiness</span> set to true.</p>
+  <p>On setting, the <code data-x="dom-select-value">value</code> attribute must run the following
+  steps:</p>
+
+  <ol>
+   <li><p>Set the <span data-x="concept-option-selectedness">selectedness</span> of all the
+   <code>option</code> elements in the <span data-x="concept-select-option-list">list of
+   options</span> to false.</p></li>
+
+   <li><p>The first <code>option</code> element in the <span
+   data-x="concept-select-option-list">list of options</span>, in <span>tree order</span>, whose
+   <span data-x="concept-option-value">value</span> is equal to the given new value, if any, must
+   have its <span data-x="concept-option-selectedness">selectedness</span> set to true and its <span
+   data-x="concept-option-dirtiness">dirtiness</span> set to true.</p></li>
+
+   <li><p>Run <span>update a <code>select</code>'s <code>selectedcontent</code></span> given this
+   <code>select</code>.</p></li>
+  </ol>
 
   <p class="note">This can result in no element having a <span
   data-x="concept-option-selectedness">selectedness</span> set to true even in the case of the
@@ -54611,16 +54619,13 @@ interface <dfn interface>HTMLOptionElement</dfn> : <span>HTMLElement</span> {
      <li><p><var>option</var>'s <span data-x="concept-option-selectedness">selectedness</span>
      is true;</p></li>
 
-     <li><p><var>select</var>'s <span>descendant <code>selectedcontent</code> elements</span> is not
-     empty;</p></li>
-
-     <li><p>The first element in <var>select</var>'s <span>descendant <code>selectedcontent</code>
-     elements</span> is not <span data-x="selectedcontent-disabled">disabled</span>,</p></li>
+     <li><p><var>select</var>'s <span data-x="select-enabled-selectedcontent">enabled
+     <code>selectedcontent</code></span> is not null,</p></li>
     </ul>
 
-    <p>then run <span>clone an option into a selectedcontent</span> given <var>option</var> and the
-    first element of <var>option</var>'s <span><code>option</code> element nearest ancestor
-    <code>select</code></span>'s <span>descendant <code>selectedcontent</code> elements</span>.</p>
+    <p>then run <span>clone an option into a selectedcontent</span> given <var>option</var> and
+    <var>select</var>'s <span data-x="select-enabled-selectedcontent">enabled
+    <code>selectedcontent</code></span>.</p>
    </li>
   </ol>
 
@@ -56328,8 +56333,50 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
   data-x="selectedcontent-disabled">disabled</dfn> state, which is a boolean, initially set to
   false.</p>
 
-  <p>To <dfn>clone an option into a selectedcontent</dfn>, given an <code>option</code> element
-  <var>option</var> and a <code>selectedcontent</code> element <var>selectedcontent</var>:</p>
+  <p>To <dfn>update a <code>select</code>'s <code>selectedcontent</code></dfn> given a
+  <code>select</code> element <var>select</var>:</p>
+
+  <ol>
+   <li><p>Let <var>selectedcontent</var> be the result of <span
+   data-x="select-enabled-selectedcontent">get a <code>select</code>'s enabled
+   <code>selectedcontent</code></span> given <var>select</var>.</p></li>
+
+   <li><p>If <var>selectedcontent</var> is null, then return.</p></li>
+
+   <li><p>Let <var>option</var> be the first <code>option</code> in
+   <var>nearestSelectAncestor</var>'s <span data-x="concept-select-option-list">list of
+   options</span> whose <span data-x="concept-option-selectedness">selectedness</span> is true, if
+   any such <code>option</code> exists, otherwise null.</p></li>
+
+   <li><p>If <var>option</var> is null, then run <span>clear a <code>selectedcontent</code></span>
+   given <var>insertedNode</var>.</p></li>
+
+   <li><p>Otherwise, run <span>clone an option into a <code>selectedcontent</code></span> given
+   <var>option</var> and <var>insertedNode</var>.</p></li>
+  </ol>
+
+  <p>To <dfn data-x="select-enabled-selectedcontent">get a <code>select</code>'s enabled
+  <code>selectedcontent</code></dfn> given a <code>select</code> element <var>select</var>:</p>
+
+  <ol>
+   <li><p>If <var>select</var> has the <code data-x="attr-select-multiple">multiple</code>
+   attribute, then return null.</p></li>
+
+   <li><p>If <var>select</var>'s <span>descendant <code>selectedcontent</code> elements</span> is
+   empty, then return null.</p></li>
+
+   <li><p>Let <var>selectedcontent</var> be the first item in <var>select</var>'s <span>descendant
+   <code>selectedcontent</code> elements</span>.</p></li>
+
+   <li><p>If <var>selectedcontent</var> is <span data-x="selectedcontent-disabled">disabled</span>,
+   then return null.</p></li>
+
+   <li><p>Return <var>selectedcontent</var>.</p></li>
+  </ol>
+
+  <p>To <dfn>clone an <code>option</code> into a <code>selectedcontent</code></dfn>, given an
+  <code>option</code> element <var>option</var> and a <code>selectedcontent</code> element
+  <var>selectedcontent</var>:</p>
 
   <ol>
    <li><p>Let <var>nodes</var> be « ».</p></li>
@@ -56357,7 +56404,7 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
    <var>documentFragment</var> within <var>selectedcontent</var>.</p></li>
   </ol>
 
-  <p>To <dfn>clear a selectedcontent</dfn> given a <code>selectedcontent</code> element
+  <p>To <dfn>clear a <code>selectedcontent</code></dfn> given a <code>selectedcontent</code> element
   <var>selectedcontent</var>:</p>
 
   <ol>
@@ -56406,24 +56453,8 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
    <var>nearestSelectAncestor</var>'s <span>descendant <code>selectedcontent</code>
    elements</span>.</p></li>
 
-   <li>
-    <p>If <var>selectedcontent</var> is not <span data-x="selectedcontent-disabled">disabled</span>
-    and <var>selectedcontent</var> is the first item in <var>nearestAncestorSelect</var>'s
-    <span>descendant <code>selectedcontent</code> elements</span>, then:</p>
-
-    <ol>
-     <li><p>Let <var>option</var> be the first <code>option</code> in
-     <var>nearestSelectAncestor</var>'s <span data-x="concept-select-option-list">list of
-     options</span> whose <span data-x="concept-option-selectedness">selectedness</span> is true, if
-     any such <code>option</code> exists, otherwise null.</p></li>
-
-     <li><p>If <var>option</var> is null, then run <span>clear a selectedcontent</span> given
-     <var>insertedNode</var>.</p></li>
-
-     <li><p>Otherwise, run <span>clone an option into a selectedcontent</span> given
-     <var>option</var> and <var>insertedNode</var>.</p></li>
-    </ol>
-   </li>
+   <li><p>Run <span>update a <code>select</code>'s <code>selectedcontent</code></span> given
+   <var>select</var>.</p></li>
   </ol>
 
   <p>The <code>selectedcontent</code> <span>HTML element removing steps</span>, given

From 4126c04ebcfb90150a2ad3fac71c025eef8db1a5 Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Mon, 16 Dec 2024 13:36:45 -0800
Subject: [PATCH 20/25] Only update first selectedcontent in tree order

---
 source | 35 +++++------------------------------
 1 file changed, 5 insertions(+), 30 deletions(-)

diff --git a/source b/source
index 36d88095e4e..8b6a40f0c68 100644
--- a/source
+++ b/source
@@ -53706,10 +53706,6 @@ interface <dfn interface>HTMLSelectElement</dfn> : <span>HTMLElement</span> {
   element, and all the <code>option</code> element children of all the <code>optgroup</code> element
   children of the <code>select</code> element, in <span>tree order</span>.</p>
 
-  <p>Every <code>select</code> element has <dfn>descendant <code>selectedcontent</code>
-  elements</dfn>, which is a <span>list</span> of <code>selectedcontent</code> elements, initially
-  « ».</p>
-
   <p>The <dfn element-attr for="select"><code data-x="attr-select-required">required</code></dfn>
   attribute is a <span>boolean attribute</span>. When specified, the user will be required to select
   a value before submitting the form.</p>
@@ -56362,11 +56358,9 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
    <li><p>If <var>select</var> has the <code data-x="attr-select-multiple">multiple</code>
    attribute, then return null.</p></li>
 
-   <li><p>If <var>select</var>'s <span>descendant <code>selectedcontent</code> elements</span> is
-   empty, then return null.</p></li>
-
-   <li><p>Let <var>selectedcontent</var> be the first item in <var>select</var>'s <span>descendant
-   <code>selectedcontent</code> elements</span>.</p></li>
+   <li><p>Let <var>selectedcontent</var> be the first <code>selectedcontent</code> element
+   <span>descendant</span> of <var>select</var> in <span>tree order</span> if any such element
+   exists; otherwise return null.</p></li>
 
    <li><p>If <var>selectedcontent</var> is <span data-x="selectedcontent-disabled">disabled</span>,
    then return null.</p></li>
@@ -56449,10 +56443,6 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
 
    <li><p>If <var>nearestSelectAncestor</var> is null, then return.</p></li>
 
-   <li><p><span data-x="list append">Append</span> <var>selectedcontent</var> to
-   <var>nearestSelectAncestor</var>'s <span>descendant <code>selectedcontent</code>
-   elements</span>.</p></li>
-
    <li><p>Run <span>update a <code>select</code>'s <code>selectedcontent</code></span> given
    <var>select</var>.</p></li>
   </ol>
@@ -56475,23 +56465,8 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
     ancestor">inclusive ancestors</span> in reverse <span>tree order</span>:</p>
 
     <ol>
-     <li>
-      <p>If <var>ancestor</var> is a <code>select</code> element, then:</p>
-
-      <ol>
-       <li><p>Let <var>wasFirst</var> be true if <var>selectedcontent</var> is the first element in
-       <var>ancestor</var>'s <span>descendant <code>selectedcontent</code> elements</span>,
-       otherwise false.</p></li>
-
-       <li><p><span data-x="list remove">remove</span> <var>selectedcontent</var> from
-       <var>ancestor</var>'s <span>descendant <code>selectedcontent</code> elements</span>.</p></li>
-
-       <li><p>If <var>wasFirst</var> is true, then run <span>clear a selectedcontent</span> given
-       <var>selectedcontent</var>.</p></li>
-
-       <li><p>Return.</p></li>
-      </ol>
-     </li>
+     <li><p>If <var>ancestor</var> is a <code>select</code> element, then run <span>clear a
+     selectedcontent</span> given <var>selectedcontent</var>.</p></li>
     </ol>
    </li>
   </ol>

From 42ef6811b41d0c20d4bf7761bad02193cf372698 Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Mon, 16 Dec 2024 13:40:37 -0800
Subject: [PATCH 21/25] fix variable names

---
 source | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/source b/source
index 8b6a40f0c68..75b6a575561 100644
--- a/source
+++ b/source
@@ -56427,7 +56427,7 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
       <p>If <var>ancestor</var> is a <code>select</code> element, then:</p>
 
       <ol>
-       <li><p>If <var>nearestAncestorSelect</var> is null, then set <var>nearestAncestorSelect</var>
+       <li><p>If <var>nearestSelectAncestor</var> is null, then set <var>nearestSelectAncestor</var>
        to <var>select</var>.</p></li>
 
        <li><p>Otherwise, set <var>selectedcontent</var>'s <span
@@ -56444,7 +56444,7 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
    <li><p>If <var>nearestSelectAncestor</var> is null, then return.</p></li>
 
    <li><p>Run <span>update a <code>select</code>'s <code>selectedcontent</code></span> given
-   <var>select</var>.</p></li>
+   <var>nearestSelectAncestor</var>.</p></li>
   </ol>
 
   <p>The <code>selectedcontent</code> <span>HTML element removing steps</span>, given

From 961fee3fe6e259854189a8284af274e1e596da7a Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Mon, 16 Dec 2024 13:41:45 -0800
Subject: [PATCH 22/25] more variable names

---
 source | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/source b/source
index 75b6a575561..7e8c2bbee7c 100644
--- a/source
+++ b/source
@@ -56340,7 +56340,7 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
    <li><p>If <var>selectedcontent</var> is null, then return.</p></li>
 
    <li><p>Let <var>option</var> be the first <code>option</code> in
-   <var>nearestSelectAncestor</var>'s <span data-x="concept-select-option-list">list of
+   <var>select</var>'s <span data-x="concept-select-option-list">list of
    options</span> whose <span data-x="concept-option-selectedness">selectedness</span> is true, if
    any such <code>option</code> exists, otherwise null.</p></li>
 

From 999a14aa6ab1c7646b3886ac265617e85439cb3e Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Tue, 17 Dec 2024 15:50:56 -0800
Subject: [PATCH 23/25] Remove removal steps

https://chromium-review.googlesource.com/c/chromium/src/+/6043186/comment/943643d9_9117fc4d/
---
 source | 24 ------------------------
 1 file changed, 24 deletions(-)

diff --git a/source b/source
index 7e8c2bbee7c..ced4e8d8bf7 100644
--- a/source
+++ b/source
@@ -56447,30 +56447,6 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
    <var>nearestSelectAncestor</var>.</p></li>
   </ol>
 
-  <p>The <code>selectedcontent</code> <span>HTML element removing steps</span>, given
-  <var>selectedcontent</var> and <var>oldParent</var>, are:</p>
-
-  <ol>
-   <li>
-    <p>For each <var>ancestor</var> of <var>selectedcontent</var>'s <span
-    data-x="ancestor">ancestors</span> in reverse <span>tree order</span>:</p>
-
-    <ol>
-     <li><p>If <var>ancestor</var> is a <code>select</code> element, then return.</p></li>
-    </ol>
-   </li>
-
-   <li>
-    <p>For each <var>ancestor</var> of <var>oldParent</var>'s <span data-x="inclusive
-    ancestor">inclusive ancestors</span> in reverse <span>tree order</span>:</p>
-
-    <ol>
-     <li><p>If <var>ancestor</var> is a <code>select</code> element, then run <span>clear a
-     selectedcontent</span> given <var>selectedcontent</var>.</p></li>
-    </ol>
-   </li>
-  </ol>
-
 
 
   <h4 split-filename="form-control-infrastructure">Form control infrastructure</h4>

From 4a175cebd5ca9569ef2a61e8b973764d5daa2b01 Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Fri, 20 Dec 2024 09:51:45 -0800
Subject: [PATCH 24/25] use more <code>

---
 source | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/source b/source
index ced4e8d8bf7..d0471be7d24 100644
--- a/source
+++ b/source
@@ -54619,8 +54619,8 @@ interface <dfn interface>HTMLOptionElement</dfn> : <span>HTMLElement</span> {
      <code>selectedcontent</code></span> is not null,</p></li>
     </ul>
 
-    <p>then run <span>clone an option into a selectedcontent</span> given <var>option</var> and
-    <var>select</var>'s <span data-x="select-enabled-selectedcontent">enabled
+    <p>then run <span>clone an <code>option</code> into a <code>selectedcontent</code></span> given
+    <var>option</var> and <var>select</var>'s <span data-x="select-enabled-selectedcontent">enabled
     <code>selectedcontent</code></span>.</p>
    </li>
   </ol>

From 730b52fa1853eb62e044e3aa2c2d1506570c6a0a Mon Sep 17 00:00:00 2001
From: Joey Arhar <jarhar@chromium.org>
Date: Fri, 20 Dec 2024 09:52:59 -0800
Subject: [PATCH 25/25] Run more updates on insertion and removal

---
 source | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 57 insertions(+), 3 deletions(-)

diff --git a/source b/source
index d0471be7d24..5c6020d70fb 100644
--- a/source
+++ b/source
@@ -56345,10 +56345,10 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
    any such <code>option</code> exists, otherwise null.</p></li>
 
    <li><p>If <var>option</var> is null, then run <span>clear a <code>selectedcontent</code></span>
-   given <var>insertedNode</var>.</p></li>
+   given <var>selectedcontent</var>.</p></li>
 
    <li><p>Otherwise, run <span>clone an option into a <code>selectedcontent</code></span> given
-   <var>option</var> and <var>insertedNode</var>.</p></li>
+   <var>option</var> and <var>selectedcontent</var>.</p></li>
   </ol>
 
   <p>To <dfn data-x="select-enabled-selectedcontent">get a <code>select</code>'s enabled
@@ -56407,6 +56407,31 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
    order</span>.</p></li>
   </ol>
 
+  <p>To <dfn>clear a <code>select</code>'s non-primary <code>selectedcontent</code> elements</dfn>,
+  given a <code>select</code> element <var>select</var>:</p>
+
+  <ol>
+   <li><p>Let <var>passedFirstSelectedcontent</var> be false.</p></li>
+
+   <li>
+    <p>For each <span>descendant</span> of <var>select</var> in <span>tree order</span>:</p>
+
+    <ol>
+     <li>
+      <p>If <var>descendant</var> is a <code>selectedcontent</code> element, then:</p>
+
+      <ol>
+       <li><p>If <var>passedFirstSelectedcontent</var> is false, then set
+       <var>passedFirstSelectedcontent</var> to true.</p></li>
+
+       <li><p>Otherwise, run <span>clear a <code>selectedcontent</code></span> given
+       <var>descendant</var>.</p></li>
+      </ol>
+     </li>
+    </ol>
+   </li>
+  </ol>
+
   <p>The <code>selectedcontent</code> <span>HTML element post-connection steps</span>, given
   <var>selectedcontent</var>, are:</p>
 
@@ -56441,10 +56466,39 @@ interface <dfn interface>HTMLSelectedContentElement</dfn> : <span>HTMLElement</s
     </ol>
    </li>
 
-   <li><p>If <var>nearestSelectAncestor</var> is null, then return.</p></li>
+   <li><p>If <var>nearestSelectAncestor</var> is null or <var>nearestSelectAncestor</var> has the
+   <code data-x="attr-select-multiple">multiple</code> attribute, then return.</p></li>
 
    <li><p>Run <span>update a <code>select</code>'s <code>selectedcontent</code></span> given
    <var>nearestSelectAncestor</var>.</p></li>
+
+   <li><p>Run <span>clear a <code>select</code>'s non-primary <code>selectedcontent</code>
+   elements</span> given <var>nearestSelectAncestor</var>.</p></li>
+  </ol>
+
+  <p>The <code>selectedcontent</code> <span>HTML element removing steps</span>, given
+  <var>selectedcontent</var> and <var>oldParent</var>, are:</p>
+
+  <ol>
+   <li>
+    <p>For each <var>ancestor</var> of <var>selectedcontent</var>'s <span
+    data-x="ancestor">ancestors</span> in reverse <span>tree order</span>:</p>
+
+    <ol>
+     <li><p>If <var>ancestor</var> is a <code>select</code> element, then return.</p></li>
+    </ol>
+   </li>
+
+   <li>
+    <p>For each <var>ancestor</var> of <var>oldParent</var>'s <span data-x="inclusive
+    ancestor">inclusive ancestors</span> in reverse <span>tree order</span>:</p>
+
+    <ol>
+     <li><p>If <var>ancestor</var> is a <code>select</code> element, then run <span>update a
+     <code>select</code>'s <code>selectedcontent</code></span> given <var>ancestor</var> and
+     return.</p></li>
+    </ol>
+   </li>
   </ol>