From ComputerCraft Wiki
|Only available prior to ComputerCraft 1.5; for later versions, see rednet.broadcast().|
Broadcasts an empty rednet message. Note that its return value indicates whether that message was sent, as opposed to whether it was received or even receivable.
|Broadcasts an empty rednet message.|
|Rednet API Functions|
|rednet.open - rednet.close - rednet.send - rednet.broadcast - rednet.receive - rednet.isOpen - rednet.host - rednet.unhost - rednet.lookup|