From 351e0e94c36866d8d4465c8dd7d3b5b3fbe96b8c Mon Sep 17 00:00:00 2001
From: Alice Boxhall <95208+alice@users.noreply.github.com>
Date: Tue, 4 Feb 2025 15:33:03 +1100
Subject: [PATCH] Begin work on specifying how referenceTarget affects ID
 lookups

---
 source | 154 ++++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 98 insertions(+), 56 deletions(-)

diff --git a/source b/source
index 213f90acbef..36548332e0b 100644
--- a/source
+++ b/source
@@ -5128,7 +5128,6 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
   </div>
 
 
-
   <h4>Keywords and enumerated attributes</h4>
 
   <p>Some attributes, called <dfn data-x="enumerated attribute" data-lt="enumerated attribute"
@@ -5187,6 +5186,85 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
   </ul>
 
 
+  <h4>Element reference attributes</h4>
+
+  <p><dfn data-x="element reference" data-lt="element reference" export>
+  Element reference</dfn> attributes refer to one or more Elements in the document.</p>
+
+  <p>The steps to <dfn export data-x="resolve-the-reference-target">resolve the reference
+  target</dfn> on an element <var>element</var> referred to by an element reference attribute
+  are:</p>
+
+  <ol>
+   <li><p>If <var>element</var> does not have a <span>shadow root</span>, or <var>element</var>'s
+   <span>shadow root</span> doesn't have a <code data-x="">referenceTarget</code>
+   property, return <var>element</var>.</p></li>
+
+   <li><p>Let <var>referenceTarget</var> be the value of <var>element</var>'s <span>shadow
+   root</span>'s <code data-x="">referenceTarget</code> property</p></li>
+
+   <li><p>Let <var>candidate</var> be the first element in <var>element</var>'s <span>shadow
+   root</span> whose <span data-x="concept-id">ID</span> matches <var>referenceTarget</var>.</p>
+   </li>
+
+   <li><p>If no such element exists, return null.</p></li>
+
+   <li><p>Return the result of <span data-x="resolve-the-reference-target">resolving the reference
+   target</span> on <var>candidate</var>.
+   </p></li>
+  </ol>
+
+  <h5>Single element reference attributes</h5>
+
+  <p><dfn data-x="single element reference attribute" data-lt="single element reference attribute"
+  export>Single element reference attributes</dfn> refer to a single Element.</p>
+
+  <p>The rules to <dfn export data-x="get the attr-associated element">get the
+  <var>attr</var>-associated element</dfn> for an element reference attribute <var>attr</var> and
+  element <var>element</var>, are:</p>
+
+  <ol>
+   <li><p>If the attribute is not specified on <var>element</var>, return null.</p></li>
+
+   <li>
+    <p>If <var>element</var> has an <span data-x="explicitly set attr-element">explicitly-set
+    <var>attr</var>-element</span> which is not null:</p>
+
+    <ol>
+     <li><p>If <var>element</var>'s <span data-x="explicitly set attr-element">explicitly-set
+     <var>attr</var>-element</span> is a <span>descendant</span> of any of <var>element</var>'s
+     <span data-x="concept-shadow-including-ancestor">shadow-including ancestors</span>, then let
+     <var>candidate</var> be <var>element</var>'s
+     <span data-x="explicitly set attr-element">explicitly-set <var>attr</var>-element</span>.</p>
+     </li>
+
+     <li><p>Otherwise, let <var>candidate</var> be null.</p></li>
+    </ol>
+
+   </li>
+
+   <li>
+    <p>Otherwise:
+
+    <ol>
+     <li><p>Let <var>value</var> be the attribute value.</p></li>
+
+     <li><p>Let <var>candidate</var> be the first element in <var>element</var>'s <span>tree</span>,
+     in <span>tree order</span> whose <span data-x="concept-id">ID</span> is <var>value</var>.</p>
+     </li>
+
+     <li><p>If no such element exists, let <var>candidate</var> be null.</p>
+     </li>
+    </ol>
+   </li>
+
+   <li>If candidate is null, return null.</li>
+
+   <li><p>Return the result of <span data-x="resolve-the-reference-target">resolving the reference
+   target</span> on <var>candidate</var>.
+   </p></li>
+  </ol>
+
 
   <h4>Numbers</h4>
 
@@ -8519,59 +8597,23 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
   name</span>:</p>
 
   <ul>
-   <li><p>Its <span>reflected target</span> has an <dfn>explicitly set
-   <var>attr</var>-element</dfn>, which is a weak reference to an element or null. It is initially
-   null.</p></li>
+   <li><p>Its <span>reflected target</span> has an <dfn export data-x="explicitly set attr-element">
+   explicitly set <var>attr</var>-element</dfn>, which is a weak reference to an element or null.
+   It is initially null.</p></li>
 
    <li>
-    <p>Its <span>reflected target</span> <var>reflectedTarget</var> has a <dfn
-    for="Element,ElementInternals" export id="attr-associated-element">get the
-    <var>attr</var>-associated element</dfn> algorithm, that runs these steps:</p>
+    <p>The getter steps are:</p>
 
     <ol>
-     <li><p>Let <var>element</var> be the result of running <var>reflectedTarget</var>'s <span>get
-     the element</span>.</p></li>
-
-     <li><p>Let <var>contentAttributeValue</var> be the result of running
-     <var>reflectedTarget</var>'s <span>get the content attribute</span>.</p></li>
-
-     <li>
-      <p>If <var>reflectedTarget</var>'s <span>explicitly set <var>attr</var>-element</span> is not
-      null:</p>
-
-      <ol>
-       <li><p>If <var>reflectedTarget</var>'s <span>explicitly set <var>attr</var>-element</span> is
-       a <span>descendant</span> of any of <var>element</var>'s <span
-       data-x="concept-shadow-including-ancestor">shadow-including ancestors</span>, then return
-       <var>reflectedTarget</var>'s <span>explicitly set <var>attr</var>-element</span>.</p></li>
-
-       <li><p>Return null.</p></li>
-      </ol>
+     <li><p>Let <var>candidate</var> be the result of running <span>this</span>'s
+     <span data-x="get the attr-associated element">get the <var>attr</var>-associated
+     element</span>.</p>
      </li>
 
-     <li>
-      <p>Otherwise, if <var>contentAttributeValue</var> is not null, return the first element
-      <var>candidate</var>, in <span>tree order</span>, that meets the following criteria:</p>
-
-      <ul>
-       <li><p><var>candidate</var>'s <span>root</span> is the same as <var>element</var>'s
-       <span>root</span>;</p></li>
-
-       <li><p><var>candidate</var>'s <span data-x="concept-ID">ID</span> is
-       <var>contentAttributeValue</var>; and</p></li>
-
-       <li><p><var>candidate</var> <span>implements</span> <var>T</var>.</p></li>
-      </ul>
-
-      <p>If no such element exists, then return null.</p>
-     </li>
-
-     <li><p>Return null.</p></li>
+     <li><p>Return the result of <span data-x="dom-retarget">retargeting</span> <var>candidate</var>
+     against <var>this</var>.</p></li>
     </ol>
-   </li>
-
-   <li><p>The getter steps are to return the result of running <span>this</span>'s <span>get the
-   <var>attr</var>-associated element</span>.</p></li>
+   <li>
 
    <li>
     <p>The setter steps are:</p>
@@ -8817,10 +8859,10 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
   </ul>
 
   <p>For those, specification authors must use the <span>reflected target</span>'s
-  <span>get the <var>attr</var>-associated element</span> and <span>get the
-  <var>attr</var>-associated elements</span>, respectively. The content attribute presence and value
-  must not be used as they cannot be fully synchronized with the <span>reflected IDL
-  attribute</span>.</p>
+  <span data-x="get the attr-associated element">get the <var>attr</var>-associated element</span>
+  and <span>get the <var>attr</var>-associated elements</span>, respectively. The content attribute
+  presence and value must not be used as they cannot be fully synchronized with the <span>reflected
+  IDL attribute</span>.</p>
 
   <p>A <span>reflected target</span>'s <span>explicitly set <var>attr</var>-element</span>,
   <span>explicitly set <var>attr</var>-elements</span>, <span>cached <var>attr</var>-associated
@@ -46424,11 +46466,11 @@ interface <dfn interface>HTMLLabelElement</dfn> : <span>HTMLElement</span> {
   be specified to indicate a form control with which the caption is to be associated. If the
   attribute is specified, the attribute's value must be the <span data-x="concept-id">ID</span> of a
   <span data-x="category-label">labelable element</span> in the same <span>tree</span> as the
-  <code>label</code> element. <span w-nodev>If the attribute is specified and there is an element in
-  the <span>tree</span> whose <span data-x="concept-id">ID</span> is equal to the value of the <code
-  data-x="attr-label-for">for</code> attribute, and the first such element in <span>tree
-  order</span> is a <span data-x="category-label">labelable element</span>, then that element is the
-  <code>label</code> element's <span>labeled control</span>.</span></p>
+  <code>label</code> element. <span w-nodev>If the attribute is specified, the <span
+  data-x="get the attr-associated element">for-associated element</span> is not null, and the <span
+  data-x="get the attr-associated element">for-associated element</span> is a <span
+  data-x="category-label">labelable element</span>, then that element is the <code>label</code>
+  element's <span>labeled control</span>.</span></p>
 
   <div w-nodev>