see: modem_message For raw modem messages sent outside of Rednet.
see: rednet.receive To wait for a Rednet message with an optional timeout and protocol filter.
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The @{rednet_message} event is fired when a message is sent over Rednet.
This event is usually handled by @{rednet.receive}, but it can also be pulled manually.
@{rednet_message} events are sent by @{rednet.run} in the top-level coroutine in response to @{modem_message} events. A @{rednet_message} event is always preceded by a @{modem_message} event. They are generated inside CraftOS rather than being sent by the ComputerCraft machine.