diff --git a/runtime/doc/intro.txt b/runtime/doc/intro.txt
index 0e0156ac6b..54999fa163 100644
--- a/runtime/doc/intro.txt
+++ b/runtime/doc/intro.txt
@@ -322,7 +322,6 @@ notation	meaning		    equivalent	decimal value(s)	~
 <Bar>		vertical bar		|	124	*<Bar>*
 <Del>		delete				127
 <CSI>		command sequence intro  ALT-Esc 155	*<CSI>*
-<xCSI>		CSI when typed in the GUI		*<xCSI>*
 
 <EOL>		end-of-line (can be <CR>, <NL> or <CR><NL>,
 		depends on system and 'fileformat')	*<EOL>*
diff --git a/src/nvim/keymap.c b/src/nvim/keymap.c
index abf016b832..f8ccb79ade 100644
--- a/src/nvim/keymap.c
+++ b/src/nvim/keymap.c
@@ -158,7 +158,6 @@ static const struct key_name_entry {
   { ESC,               "Esc" },
   { ESC,               "Escape" },      // Alternative name
   { CSI,               "CSI" },
-  { K_CSI,             "xCSI" },
   { '|',               "Bar" },
   { '\\',              "Bslash" },
   { K_DEL,             "Del" },
diff --git a/src/nvim/keymap.h b/src/nvim/keymap.h
index 5a74d1dc00..ec18dc64b5 100644
--- a/src/nvim/keymap.h
+++ b/src/nvim/keymap.h
@@ -220,7 +220,7 @@ enum key_extra {
   KE_KINS = 79,             // keypad Insert key
   KE_KDEL = 80,              // keypad Delete key
 
-  KE_CSI = 81,              // CSI typed directly
+  KE_CSI = 81,              // CSI typed directly (no longer produced by Nvim)
   KE_SNR = 82,              // <SNR>
   KE_PLUG = 83,             // <Plug>
   KE_CMDWIN = 84,            // open command-line window from Command-line Mode
@@ -435,7 +435,6 @@ enum key_extra {
 #define K_MOUSELEFT     TERMCAP2KEY(KS_EXTRA, KE_MOUSELEFT)
 #define K_MOUSERIGHT    TERMCAP2KEY(KS_EXTRA, KE_MOUSERIGHT)
 
-#define K_CSI           TERMCAP2KEY(KS_EXTRA, KE_CSI)
 #define K_SNR           TERMCAP2KEY(KS_EXTRA, KE_SNR)
 #define K_PLUG          TERMCAP2KEY(KS_EXTRA, KE_PLUG)
 #define K_CMDWIN        TERMCAP2KEY(KS_EXTRA, KE_CMDWIN)