diff --git a/html-aam/index.html b/html-aam/index.html
index 6fbb93cdf..b7e3093c5 100644
--- a/html-aam/index.html
+++ b/html-aam/index.html
@@ -4697,7 +4697,10 @@ <h4 id="el-legend">`legend`</h4>
               </th>
               <td>
                 <div class="role"><span class="type">Roles:</span> `ROLE_SYSTEM_STATICTEXT`; `IA2_ROLE_LABEL`</div>
-                <div class="relations"><span class="type">Relations:</span> `IA2_RELATION_LABEL_FOR` with the parent <a href="#el-fieldset">`fieldset`</a></div>
+                <div class="relations">
+                  <span class="type">Relations:</span> `IA2_RELATION_LABEL_FOR` with the parent <a href="#el-fieldset">`fieldset`</a> 
+                  or <a href="#el-optgroup">`optgroup`</a>
+                </div>
               </td>
             </tr>
             <tr>
@@ -4707,7 +4710,8 @@ <h4 id="el-legend">`legend`</h4>
                 <div class="properties">
                   <span class="type">Other properties:</span>
                   The `LabeledBy` property for the parent
-                  <a href="#el-fieldset">`fieldset`</a> points to the UIA element for the `legend` element.
+                  <a href="#el-fieldset">`fieldset`</a> or <a href="#el-optgroup">`optgroup`</a> points to the 
+                  UIA element for the `legend` element.
                 </div>
               </td>
             </tr>
@@ -4717,7 +4721,8 @@ <h4 id="el-legend">`legend`</h4>
                 <div class="role"><span class="type">Role:</span> `ATK_ROLE_LABEL`</div>
                 <div class="relations">
                   <span class="type">Relations:</span>
-                  `ATK_RELATION_LABEL_FOR` with parent <a href="#el-fieldset">`fieldset`</a> element
+                  `ATK_RELATION_LABEL_FOR` with parent <a href="#el-fieldset">`fieldset`</a> 
+                  or <a href="#el-optgroup">`optgroup`</a> element
                 </div>
               </td>
             </tr>
@@ -16192,12 +16197,34 @@ <h4>`fieldset` Element Accessible Name Computation</h4>
             </li>
             <li>
               If the <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a> is still empty, then: if the `fieldset` element has a
-              <a href="https://dom.spec.whatwg.org/#concept-tree-child">child</a> that is a <code>legend</code> element, then use the subtree of the first such element.
+              <a href="https://dom.spec.whatwg.org/#concept-tree-child">child</a> that is a <code>legend</code> element, then use the subtree of the first such element in the accessibility tree.
             </li>
             <li>If the <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a> is still empty, then:, if the `fieldset` element has a `title` attribute, then use that attribute.</li>
             <li>Otherwise, there is no <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a>.</li>
           </ol>
         </section>
+        <section>
+          <h4>`optgroup` Element Accessible Name Computation</h4>
+          <ol>
+            <li>
+              If the `optgroup` element has an <a data-cite="wai-aria-1.2/#aria-label">`aria-label`</a> or an <a data-cite="wai-aria-1.2/#aria-labelledby">`aria-labelledby`</a> attribute the
+              <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a> is to be calculated using the algorithm defined in
+              <a href="" class="accname">Accessible Name and Description: Computation and API Mappings</a>.
+            </li>
+            <li>
+              If the <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a> is still empty, then: if the `optgroup` element has a
+              <a href="https://dom.spec.whatwg.org/#concept-tree-child">child</a> that is a <code>legend</code> element, then use the subtree of the first such element in the accessibility tree.
+            </li>
+            <li>
+              If the <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a> is still empty, and there is no child `legend` element, then: 
+              if the `optgroup` element has a <a data-cite="html/form-elements.html#attr-optgroup-label">label</a> attribute use the value of that attribute, which renders as the visible label of the `optgroup`.
+            </li>
+            <li>
+              If the <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a> is still empty, then: if the `optgroup` element has a `title` attribute, then use that attribute.
+            </li>
+            <li>Otherwise, there is no <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a>.</li>
+          </ol>
+        </section>
         <section>
           <h4>`output` Element Accessible Name Computation</h4>
           <ol>
@@ -16400,6 +16427,19 @@ <h3>Accessible Description Computation</h3>
                 <a data-cite="accname-1.2/#mapping_additional_nd_te">text equivalent computation</a> of the subtree of the first `caption` element if it was not used as the
                 <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a>.
               </li>
+              <li>
+                an `optgroup` element which has a visible label rendered by its `label` attribute, a <a href="https://dom.spec.whatwg.org/#concept-tree-child">child</a> `legend` element, or both:
+                  <ol>
+                    <li>
+                      use the value of the `label` attribute if it was not used as the 
+                      <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a>
+                    </li>
+                    <li>
+                      or use the <a data-cite="accname-1.2/#mapping_additional_nd_te">text equivalent computation</a> of the subtree of the 
+                      first `legend` element if it was not used as the <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a>.
+                    </li>
+                  </ol>
+              </li>
               <li>
                 a `summary` element, use the <a data-cite="accname-1.2/#mapping_additional_nd_te">text equivalent computation</a> of its subtree if it was not used as the
                 <a data-cite="accname-1.2/#dfn-accessible-name">accessible name</a>.