1 files changed, 3 insertions, 0 deletions
diff --git a/synapse/api/constants.py b/synapse/api/constants.py
index bc04a0755b..89723d24fa 100644
--- a/synapse/api/constants.py
+++ b/synapse/api/constants.py
@@ -230,6 +230,9 @@ class EventContentFields:
     # The authorising user for joining a restricted room.
     AUTHORISING_USER: Final = "join_authorised_via_users_server"
 
+    # an unspecced field added to to-device messages to identify them uniquely-ish
+    TO_DEVICE_MSGID: Final = "org.matrix.msgid"
+
 
 class RoomTypes:
     """Understood values of the room_type field of m.room.create events."""