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*
diff --git a/runtime/doc/tags b/runtime/doc/tags
index 75b00aa..7d54ee9 100644
--- a/runtime/doc/tags
+++ b/runtime/doc/tags
@@ -4621,6 +4621,7 @@
 E1539	vim9.txt	/*E1539*
 E154	helphelp.txt	/*E154*
 E1540	eval.txt	/*E1540*
+E1541	vi_diff.txt	/*E1541*
 E155	sign.txt	/*E155*
 E156	sign.txt	/*E156*
 E157	sign.txt	/*E157*
diff --git a/runtime/doc/vi_diff.txt b/runtime/doc/vi_diff.txt
index b96f779..46db57a 100644
--- a/runtime/doc/vi_diff.txt
+++ b/runtime/doc/vi_diff.txt
@@ -1,4 +1,4 @@
-*vi_diff.txt*   For Vim version 9.1.  Last change: 2024 Nov 10
+*vi_diff.txt*   For Vim version 9.1.  Last change: 2025 Mar 28
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -91,8 +91,11 @@
 Maximum lhs of a mapping   50 characters.
 Number of different highlighting types: over 30000
 Range of a Number variable:  -2147483648 to 2147483647 (might be more on 64
-			   bit systems)
+			   bit systems)  See also: |v:numbermax|,
+			   |v:numbermin| and |v:numbersize|
 Maximum length of a line in a tags file: 512 bytes.
+							*E1541*
+Maximum value for |/\U| and |/\%U|: 2147483647 (for 32bit integer).
 
 Information for undo and text in registers is kept in memory, thus when making
 (big) changes the amount of (virtual) memory available limits the number of