"title": "A receipt for a message. N.B. not implemented in Synapse, and superceded in\nv2 CS API by the ``relates_to`` event field.",
"description": "Feedback events are events sent to acknowledge a message in some way. There\nare two supported acknowledgements: ``delivered`` (sent when the event has\nbeen received) and ``read`` (sent when the event has been observed by the\nend-user). The ``target_event_id`` should reference the ``m.room.message``\nevent being acknowledged.",