diff --git a/index.html b/index.html
index 1bb6b8c..c393643 100644
--- a/index.html
+++ b/index.html
@@ -35,7 +35,7 @@
       <tr>
         <td><a href="zkat/schema-v2/draft-marchan-kdl2.html" class="html draft-marchan-kdl2" title="The KDL Document Language (HTML)">KDL</a></td>
         <td><a href="zkat/schema-v2/draft-marchan-kdl2.txt" class="txt draft-marchan-kdl2" title="The KDL Document Language (Text)">plain text</a></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/schema-v2/draft-marchan-kdl2.txt" class="diff draft-marchan-kdl2">diff with main</a></td>
+        <td>same as main</td>
       </tr>
     </table>
     <h2>Preview for branch <a href="zkat/utf-8-must">zkat/utf-8-must</a></h2>
diff --git a/zkat/schema-v2/draft-marchan-kdl2.html b/zkat/schema-v2/draft-marchan-kdl2.html
index c3fa963..917b2b9 100644
--- a/zkat/schema-v2/draft-marchan-kdl2.html
+++ b/zkat/schema-v2/draft-marchan-kdl2.html
@@ -1347,7 +1347,7 @@ depending on the characters used.<a href="#section-2-4" class="pilcrow">¶</a></
 <p id="section-3.1-1">The toplevel concept of KDL is a Document. A Document is composed of zero or
 more Nodes (<a href="#node" class="auto internal xref">Section 3.2</a>), separated by newlines and whitespace, and eventually
 terminated by an EOF.<a href="#section-3.1-1" class="pilcrow">¶</a></p>
-<p id="section-3.1-2">All KDL documents should be UTF-8 encoded and conform to the specifications in
+<p id="section-3.1-2">All KDL documents MUST be encoded in UTF-8 and conform to the specifications in
 this document.<a href="#section-3.1-2" class="pilcrow">¶</a></p>
 <div id="example">
 <section id="section-3.1.1">
@@ -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}
+// &gt;U+10FFFF:      &gt;1          _____           1  &gt;0          ____
+
 
 raw-string := '#' raw-string-quotes '#' | '#' raw-string '#'
 raw-string-quotes :=
diff --git a/zkat/schema-v2/draft-marchan-kdl2.txt b/zkat/schema-v2/draft-marchan-kdl2.txt
index 9dd7e11..0bdf991 100644
--- a/zkat/schema-v2/draft-marchan-kdl2.txt
+++ b/zkat/schema-v2/draft-marchan-kdl2.txt
@@ -137,7 +137,7 @@ Table of Contents
    zero or more Nodes (Section 3.2), separated by newlines and
    whitespace, and eventually terminated by an EOF.
 
-   All KDL documents should be UTF-8 encoded and conform to the
+   All KDL documents MUST be encoded in UTF-8 and conform to the
    specifications in this document.
 
 3.1.1.  Example
@@ -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 :=