diff --git a/source b/source
index 8dfc29a8f0b..737fef9a0c5 100644
--- a/source
+++ b/source
@@ -5430,31 +5430,34 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
   <p class="note">Multiple keywords can map to the same state.</p>
 
   <div algorithm>
-  <p>To determine the state of an attribute, use the following steps:</p>
+  <p>To <dfn>determine the state of an attribute</dfn> given an attribute value <var>value</var> and
+  a set of keyword/state mappings and special states defined in the specification
+  <var>attributeDefinition</var>, use the following steps:</p>
 
   <ol>
    <li>
-    <p>If the attribute is not specified:</p>
+    <p>If <var>value</var> is null (meaning the attribute is not specified):</p>
 
     <ol>
-     <li><p>If the attribute has a <i data-x="missing value default">missing value default</i>
-     state defined, then return that <i data-x="missing value default">missing value default</i>
-     state.</p></li>
+     <li><p>If <var>attributeDefinition</var> has a <i data-x="missing value default">missing value
+     default</i> state defined, then return that <i data-x="missing value default">missing value
+     default</i> state.</p></li>
 
      <li><p>Otherwise, return no state.</p></li>
     </ol>
    </li>
 
-   <li><p>If the attribute's value is an <span>ASCII case-insensitive</span> match for one of the
-   keywords defined for the attribute, then return the state represented by that keyword.</p></li>
+   <li><p>If <var>value</var> is an <span>ASCII case-insensitive</span> match for one of the
+   keywords defined for the attribute in <var>attributeDefinition</var>, then return the state
+   represented by that keyword.</p></li>
 
-   <li><p>If the attribute has an <i data-x="empty value default">empty value default</i> state
-   defined and the attribute's value is the empty string, then return that <i data-x="empty value
-   default">empty value default</i> state.</p></li>
+   <li><p>If <var>attributeDefinition</var> has an <i data-x="empty value default">empty value
+   default</i> state defined and <var>value</var> is the empty string, then return that <i
+   data-x="empty value default">empty value default</i> state.</p></li>
 
-   <li><p>If the attribute has an <i data-x="invalid value default">invalid value default</i> state
-   defined, then return that <i data-x="invalid value default">invalid value default</i>
-   state.</p></li>
+   <li><p>If <var>attributeDefinition</var> has an <i data-x="invalid value default">invalid value
+   default</i> state defined, then return that <i data-x="invalid value default">invalid value
+   default</i> state.</p></li>
 
    <li><p>Return no state.</p></li>
   </ol>
@@ -8679,14 +8682,17 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
       values</span>:</p>
 
       <ol>
-       <li><p>If <var>contentAttributeValue</var> does not correspond to any state of
-       <var>attributeDefinition</var> (e.g., it is null and there is no <i data-x="missing value
-       default">missing value default</i>), or if it is in a state of
-       <var>attributeDefinition</var> with no associated keyword value, then return the empty
-       string.</p></li>
-
-       <li><p>Return the <span>canonical keyword</span> for the state of
-       <var>attributeDefinition</var> that <var>contentAttributeValue</var> corresponds to.</p></li>
+       <li><p>Let <var>attributeState</var> be the result of <span>determine the state of an
+       attribute</span> given <var>contentAttributeValue</var> and
+       <var>attributeDefinition</var>.</p></li>
+
+       <li><p>If <var>attributeState</var> is no state (e.g., because the attribute is not present
+       and there is no <i data-x="missing value default">missing value default</i>), or if
+       <var>attributeState</var> is a state of <var>attributeDefinition</var> with no associated
+       keyword value, then return the empty string.</p></li>
+
+       <li><p>Return the <span>canonical keyword</span> for <var>attributeState</var> in
+       <var>attributeDefinition</var>.</p></li>
       </ol>
      </li>
 
@@ -8731,14 +8737,18 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
        <li><p><span>Assert</span>: the <span>reflected IDL attribute</span> is <span>limited to only
        known values</span>.</p></li>
 
-       <li><p><span>Assert</span>: <var>contentAttributeValue</var> corresponds to a state of
+       <li><p>Let <var>attributeState</var> be the result of <span>determine the state of an
+       attribute</span> given <var>contentAttributeValue</var> and
        <var>attributeDefinition</var>.</p></li>
 
-       <li><p>If <var>contentAttributeValue</var> corresponds to a state of
-       <var>attributeDefinition</var> with no associated keyword value, then return null.</p></li>
+       <li><p>If <var>attributeState</var> is no state, or if <var>attributeState</var> is a state
+       of <var>attributeDefinition</var> with no associated keyword value, then return
+       null.</p></li>
+
+       <li><p><span>Assert</span>: <var>contentAttributeValue</var> is not null.</p></li>
 
-       <li><p>Return the <span>canonical keyword</span> for the state of
-       <var>attributeDefinition</var> that <var>contentAttributeValue</var> corresponds to.</p></li>
+       <li><p>Return the <span>canonical keyword</span> for <var>attributeState</var> in
+       <var>attributeDefinition</var>.</p></li>
       </ol>
      </li>