diff --git a/source b/source
index 9f6bfcc10b4..dd88f2c2589 100644
--- a/source
+++ b/source
@@ -148711,9 +148711,11 @@ progress { appearance: auto; }</code></pre>
 
    <li><p>A <dfn>select popover</dfn>, which is a <code>div</code> element. It is appended to the
    <code>select</code>'s <span>shadow root</span> as the second child, after the <span>select button
-   slot</span>. The <code>select</code> element's <span>'::picker'</span> pseudo-element is the
-   <span>select popover</span> if the <span data-x="picker form control identifier">provided
-   argument</span> is <code data-x="">select</code>.</p></li>
+   slot</span>. The <span>select popover</span> has the <code data-x="attr-popover">popover</code>
+   attribute set to <code data-x="attr-popover-auto">auto</code>. The <code>select</code> element's
+   <span>'::picker'</span> pseudo-element is the <span>select popover</span> if the <span
+   data-x="picker form control identifier">provided argument</span> is <code
+   data-x="">select</code>.</p></li>
 
    <li><p>A <dfn>select popover slot</dfn>, which is a <code>slot</code> element. It is appended to
    the <span>select popover</span>. It is <span>expected</span> to take all child nodes of the