diff --git a/API.md b/API.md
index fe4be2dd3..5eda0f12e 100644
--- a/API.md
+++ b/API.md
@@ -40,3 +40,4 @@ This section explains all the used groups in this subgame.
 * `clock=1`: Clock
 * `compass`: Compass (rating doesn't matter)
 * `rail=1`: Rail
+* `music_record`: Music Disc (rating is track ID)