diff --git a/protocol.md b/protocol.md
index a44e0de..9732be8 100644
--- a/protocol.md
+++ b/protocol.md
@@ -61,6 +61,7 @@ Two wire UART 115200 8n1
   * 0x23 - External BMS (ESC translates it to/from 0x22 but forwards to/from external port)
   * 0x00 - ? - ESC handles it as 0x20
   * 0x01 - ?
+  * 0x3D, 0x3E, 0x3F - Application
 * bDstAddr - destination address: same as above
 * bCmd - command, see below
 * bArg - argument, depends on command type