diff --git a/runtime/doc/pattern.txt b/runtime/doc/pattern.txt
index f11040c..857a3e6 100644
--- a/runtime/doc/pattern.txt
+++ b/runtime/doc/pattern.txt
@@ -1,4 +1,4 @@
-*pattern.txt*   For Vim version 9.1.  Last change: 2025 Mar 21
+*pattern.txt*   For Vim version 9.1.  Last change: 2025 Mar 28
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -1222,7 +1222,8 @@
 		\o40	octal number of character up to 0o377
 		\x20	hexadecimal number of character up to 0xff
 		\u20AC	hex. number of multibyte character up to 0xffff
-		\U1234	hex. number of multibyte character up to 0xffffffff
+		\U1234	hex. number of multibyte character up to 8 characters
+			0xffffffff |E1541|
 	  NOTE: The other backslash codes mentioned above do not work inside
 	  []!
 	- Matching with a collection can be slow, because each character in
@@ -1263,7 +1264,8 @@
 \%u20AC	Matches the character specified with up to four hexadecimal
 	characters.
 \%U1234abcd	Matches the character specified with up to eight hexadecimal
-	characters, up to 0x7fffffff
+	characters, up to 0x7fffffff (the maximum allowed value is INT_MAX
+	|E1541|, but the maximum valid Unicode codepoint is U+10FFFF).
 
 ==============================================================================
 7. Ignoring case in a pattern					*/ignorecase*