1 files changed, 10 insertions, 0 deletions

diff --git a/docs/feature_split_keyboard.md b/docs/feature_split_keyboard.md
index b23411420..c285e353d 100644
--- a/docs/feature_split_keyboard.md
+++ b/docs/feature_split_keyboard.md
@@ -181,6 +181,16 @@ If you're having issues with serial communication, you can change this value, as
 * **`4`**: about 26kbps
 * **`5`**: about 20kbps
 
+```c
+#define SPLIT_MODS_ENABLE
+```
+
+This enables transmitting modifier state (normal, weak and oneshot) to the non
+primary side of the split keyboard.  This adds a few bytes of data to the split
+communication protocol and may impact the matrix scan speed when enabled.
+The purpose of this feature is to support cosmetic use of modifer state (e.g.
+displaying status on an OLED screen).
+
 ###  Hardware Configuration Options
 
 There are some settings that you may need to configure, based on how the hardware is set up.