1 files changed, 16 insertions, 0 deletions

diff --git a/docs/feature_split_keyboard.md b/docs/feature_split_keyboard.md
index b23411420..90af3930f 100644
--- a/docs/feature_split_keyboard.md
+++ b/docs/feature_split_keyboard.md
@@ -181,6 +181,22 @@ 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).
+
+```c
+#define SPLIT_TRANSPORT_MIRROR
+```
+
+This mirrors the master side matrix to the slave side for features that react or require knowledge of master side key presses on the slave side.  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 key events (e.g. RGB reacting to Keypresses).
+
 ###  Hardware Configuration Options
 
 There are some settings that you may need to configure, based on how the hardware is set up.