diff --git a/runtime/doc/index.txt b/runtime/doc/index.txt
index 7da8066..f0e8f30 100644
--- a/runtime/doc/index.txt
+++ b/runtime/doc/index.txt
@@ -1396,6 +1396,7 @@
 |:lfdo|		:lfd[o]		execute command in each file in location list
 |:left|		:le[ft]		left align lines
 |:leftabove|	:lefta[bove]	make split window appear left or above
+|:legacy|	:leg[acy]	make following command use legacy script syntax
 |:let|		:let		assign a value to a variable or option
 |:lexpr|	:lex[pr]	read locations from expr and jump to first
 |:lfile|	:lf[ile]	read file with locations and jump to first
diff --git a/runtime/doc/vim9.txt b/runtime/doc/vim9.txt
index 0fc7bf5..0a2ea62 100644
--- a/runtime/doc/vim9.txt
+++ b/runtime/doc/vim9.txt
@@ -61,12 +61,17 @@
 rewrite old scripts, they keep working as before.  You may want to use a few
 `:def` functions for code that needs to be fast.
 
-						*:vim9* *:vim9cmd*
-:vim9[cmd] {cmd}
+:vim9[cmd] {cmd}				*:vim9* *:vim9cmd*
 		Execute {cmd} using Vim9 script syntax and semantics.
 		Useful when typing a command and in a legacy script or
 		function.
 
+:leg[acy] {cmd}					*:leg* *:legacy*
+		Execute {cmd} using legacy script syntax and semantics.  Only
+		useful in a Vim9 script or a :def function.
+		Note that {cmd} cannot use local variables, since it is parsed
+		with legacy expression syntax.
+
 ==============================================================================
 
 2. Differences from legacy Vim script			*vim9-differences*