diff --git a/draft-marchan-kdl2.html b/draft-marchan-kdl2.html
index c47665d..6a726a2 100644
--- a/draft-marchan-kdl2.html
+++ b/draft-marchan-kdl2.html
@@ -2803,10 +2803,13 @@ string-character :=
     [^\\"] - disallowed-literal-code-points
 ws-escape := '\\' (unicode-space | newline)+
 hex-digit := [0-9a-fA-F]
-hex-unicode := hex-digit{1, 6} - surrogates
-surrogates := [dD][8-9a-fA-F]hex-digit{2}
-// U+D800-DFFF: D  8         00
-//              D  F         FF
+hex-unicode := hex-digit{1, 6} - surrogate - above-max-scalar  // Unicode Scalar Value in hex₁₆, leading 0s allowed within length ≤ 6
+surrogate := [0]{0, 2} [dD] [8-9a-fA-F] hex-digit{2}
+//  U+D800-DFFF:         D   8          00
+//                       D   F          FF
+above-max-scalar = [2-9a-fA-F] hex-digit{5} | [1] [1-9a-fA-F] hex-digit{4}
+// >U+10FFFF:      >1          _____           1  >0          ____
+
 
 raw-string := '#' raw-string-quotes '#' | '#' raw-string '#'
 raw-string-quotes :=
diff --git a/draft-marchan-kdl2.txt b/draft-marchan-kdl2.txt
index 50196dd..7f66244 100644
--- a/draft-marchan-kdl2.txt
+++ b/draft-marchan-kdl2.txt
@@ -1111,10 +1111,13 @@ Table of Contents
        [^\\"] - disallowed-literal-code-points
    ws-escape := '\\' (unicode-space | newline)+
    hex-digit := [0-9a-fA-F]
-   hex-unicode := hex-digit{1, 6} - surrogates
-   surrogates := [dD][8-9a-fA-F]hex-digit{2}
-   // U+D800-DFFF: D  8         00
-   //              D  F         FF
+   hex-unicode := hex-digit{1, 6} - surrogate - above-max-scalar  // Unicode Scalar Value in hex₁₆, leading 0s allowed within length ≤ 6
+   surrogate := [0]{0, 2} [dD] [8-9a-fA-F] hex-digit{2}
+   //  U+D800-DFFF:         D   8          00
+   //                       D   F          FF
+   above-max-scalar = [2-9a-fA-F] hex-digit{5} | [1] [1-9a-fA-F] hex-digit{4}
+   // >U+10FFFF:      >1          _____           1  >0          ____
+
 
    raw-string := '#' raw-string-quotes '#' | '#' raw-string '#'
    raw-string-quotes :=
diff --git a/index.html b/index.html
index d30dc8a..1bb6b8c 100644
--- a/index.html
+++ b/index.html
@@ -43,7 +43,7 @@
       <tr>
         <td><a href="zkat/utf-8-must/draft-marchan-kdl2.html" class="html draft-marchan-kdl2" title="The KDL Document Language (HTML)">KDL</a></td>
         <td><a href="zkat/utf-8-must/draft-marchan-kdl2.txt" class="txt draft-marchan-kdl2" title="The KDL Document Language (Text)">plain text</a></td>
-        <td>same as main</td>
+        <td><a href="https://author-tools.ietf.org/api/iddiff?url_1=https://kdl-org.github.io/kdl/draft-marchan-kdl2.txt&amp;url_2=https://kdl-org.github.io/kdl/zkat/utf-8-must/draft-marchan-kdl2.txt" class="diff draft-marchan-kdl2">diff with main</a></td>
       </tr>
     </table>
     <script>