diff --git a/runtime/doc/syntax.txt b/runtime/doc/syntax.txt
index f2c03c4..513fdac 100644
--- a/runtime/doc/syntax.txt
+++ b/runtime/doc/syntax.txt
@@ -1,4 +1,4 @@
-*syntax.txt*	For Vim version 9.1.  Last change: 2025 May 17
+*syntax.txt*	For Vim version 9.1.  Last change: 2025 May 21
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -3553,6 +3553,10 @@
 <   sh: Bourne shell >
 	let g:is_sh	   = 1
 
+Specific shell features are automatically enabled based on the shell detected
+from the shebang line ("#! ...").  For KornShell Vim detects different shell
+features for mksh, ksh88, ksh93, ksh93u, ksh93v, and ksh2020.
+
 If there's no "#! ..." line, and the user hasn't availed himself/herself of a
 default sh.vim syntax setting as just shown, then syntax/sh.vim will assume
 the POSIX shell syntax.  No need to quote RFCs or market penetration