View Source BlueHeron.ATT.PrepareWriteResponse (blue_heron v0.5.4)
The ATT_PREPARE_WRITE_RSP PDU is sent in response to a received ATT_PREPARE_WRITE_REQ PDU and acknowledges that the value has been successfully received and placed in the prepare write queue.
Bluetooth Spec v5.2, vol 3, Part F, 3.4.6.2