diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index 46819d6..b9dd4d2 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -1,4 +1,4 @@
-*builtin.txt*	For Vim version 9.1.  Last change: 2024 May 18
+*builtin.txt*	For Vim version 9.1.  Last change: 2024 May 20
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -4341,10 +4341,12 @@
 		"bufnum" is the buffer number.
 		"lnum" and "col" are the position in the buffer.  The first
 		column is 1.
-		The "off" number is zero, unless 'virtualedit' is used.  Then
-		it is the offset in screen columns from the start of the
-		character.  E.g., a position within a <Tab> or after the last
-		character.
+		If the "off" number of a starting position is non-zero, it is
+		the offset in screen columns from the start of the character.
+		E.g., a position within a <Tab> or after the last character.
+		If the "off" number of an ending position is non-zero, it is
+		the character's number of cells included in the selection,
+		otherwise the whole character is included.
 
 		Can also be used as a |method|: >
 			getpos('.')->getregionpos(getpos("'a"))