diff --git a/source b/source
index fb2f73ec63d..f5f93fd5276 100644
--- a/source
+++ b/source
@@ -3762,6 +3762,19 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
 
    </dd>
 
+
+   <dt>Payment Request API</dt>
+
+   <dd>
+    <p>The following feature is defined in the <cite>Payment Request API</cite> specification:
+    <ref spec=PAYMENTREQUEST></p>
+
+    <ul class="brief">
+     <li><dfn data-x-href="https://w3c.github.io/browser-payment-api/#paymentrequest-interface"><code>PaymentRequest</code></dfn> interface</li>
+    </ul>
+   </dd>
+
+
    <dt>MathML</dt>
 
    <dd>
@@ -28044,6 +28057,7 @@ href="?audio">audio&lt;/a> test instead.)&lt;/p></pre>
    <dd><code data-x="attr-iframe-name">name</code></dd>
    <dd><code data-x="attr-iframe-sandbox">sandbox</code></dd>
    <dd><code data-x="attr-iframe-allowfullscreen">allowfullscreen</code></dd>
+   <dd><code data-x="attr-iframe-allowpaymentrequest">allowpaymentrequest</code></dd>
    <dd><code data-x="attr-iframe-allowusermedia">allowusermedia</code></dd>
    <dd><code data-x="attr-dim-width">width</code></dd>
    <dd><code data-x="attr-dim-height">height</code></dd>
@@ -28057,6 +28071,7 @@ interface <dfn>HTMLIFrameElement</dfn> : <span>HTMLElement</span> {
   [<span>CEReactions</span>] attribute DOMString <span data-x="dom-iframe-name">name</span>;
   [<span>CEReactions</span>, SameObject, PutForwards=<span data-x="dom-DOMTokenList-value">value</span>] readonly attribute <span>DOMTokenList</span> <span data-x="dom-iframe-sandbox">sandbox</span>;
   [<span>CEReactions</span>] attribute boolean <span data-x="dom-iframe-allowFullscreen">allowFullscreen</span>;
+  [<span>CEReactions</span>] attribute boolean <span data-x="dom-iframe-allowPaymentRequest">allowPaymentRequest</span>;
   [<span>CEReactions</span>] attribute boolean <span data-x="dom-iframe-allowUserMedia">allowUserMedia</span>;
   [<span>CEReactions</span>] attribute DOMString <span data-x="dom-dim-width">width</span>;
   [<span>CEReactions</span>] attribute DOMString <span data-x="dom-dim-height">height</span>;
@@ -28574,6 +28589,11 @@ interface <dfn>HTMLIFrameElement</dfn> : <span>HTMLElement</span> {
 
   </div>
 
+  <p>The <dfn><code data-x="attr-iframe-allowpaymentrequest">allowpaymentrequest</code></dfn>
+  attribute is a <span>boolean attribute</span>. When specified, it indicates that
+  <code>Document</code> objects in the <code>iframe</code> element's <span>browsing context</span>
+  are to be allowed to use the <code>PaymentRequest</code> interface to make payment requests.</p>
+
   <p>The <dfn><code data-x="attr-iframe-allowusermedia">allowusermedia</code></dfn> attribute is a
   <span>boolean attribute</span>. When specified, it indicates that <code>Document</code> objects in
   the <code>iframe</code> element's <span>browsing context</span> are to be allowed to use <code
@@ -28650,6 +28670,10 @@ interface <dfn>HTMLIFrameElement</dfn> : <span>HTMLElement</span> {
   must <span>reflect</span> the <code data-x="attr-iframe-allowfullscreen">allowfullscreen</code>
   content attribute.</p>
 
+  <p>The <dfn><code data-x="dom-iframe-allowPaymentRequest">allowPaymentRequest</code></dfn> IDL
+  attribute must <span>reflect</span> the <code
+  data-x="attr-iframe-allowpaymentrequest">allowpaymentrequest</code> content attribute.</p>
+
   <p>The <dfn><code data-x="dom-iframe-allowUserMedia">allowUserMedia</code></dfn> IDL attribute
   must <span>reflect</span> the <code data-x="attr-iframe-allowusermedia">allowusermedia</code>
   content attribute.</p>
@@ -114878,6 +114902,7 @@ interface <dfn>External</dfn> {
          <code data-x="attr-iframe-name">name</code>;
          <code data-x="attr-iframe-sandbox">sandbox</code>;
          <code data-x="attr-iframe-allowfullscreen">allowfullscreen</code>;
+         <code data-x="attr-iframe-allowpaymentrequest">allowpaymentrequest</code>;
          <code data-x="attr-iframe-allowusermedia">allowusermedia</code>;
          <code data-x="attr-dim-width">width</code>;
          <code data-x="attr-dim-height">height</code>;
@@ -116375,6 +116400,11 @@ interface <dfn>External</dfn> {
      <td> <code data-x="attr-iframe-allowfullscreen">iframe</code>
      <td> Whether to allow the <code>iframe</code>'s contents to use <code data-x="dom-element-requestFullscreen">requestFullscreen()</code>
      <td> <span>Boolean attribute</span>
+    <tr>
+     <th> <code data-x="">allowpaymentrequest</code>
+     <td> <code data-x="attr-iframe-allowpaymentrequest">iframe</code>
+     <td> Whether the <code>iframe</code>'s contents are allowed to use the <code>PaymentRequest</code> interface to make payment requests
+     <td> <span>Boolean attribute</span>
     <tr>
      <th> <code data-x="">allowusermedia</code>
      <td> <code data-x="attr-iframe-allowusermedia">iframe</code>
@@ -119057,6 +119087,9 @@ INSERT INTERFACES HERE
    <dt id="refsPAGEVIS">[PAGEVIS]</dt>
    <dd>(Non-normative) <cite><a href="https://w3c.github.io/web-performance/specs/PageVisibility/Overview.html">Page Visibility</a></cite>, J. Mann, A. Jain. W3C.</dd>
 
+   <dt id="refsPAYMENTREQUEST">[PAYMENTREQUEST]</dt>
+   <dd><cite><a href="https://w3c.github.io/browser-payment-api/">Payment Request API</a></cite>, A. Bateman, Z. Koch, R. McElmurry. W3C.</dd>
+
    <dt id="refsPDF">[PDF]</dt>
    <dd>(Non-normative) <cite><a href="https://www.adobe.com/content/dam/Adobe/en/devnet/acrobat/pdfs/PDF32000_2008.pdf">Document management &mdash; Portable document format &mdash; Part 1: PDF</a></cite>. ISO.</dd>