HAARP (High-Frequency Active Auroral Research Program) is a high-powered radio transmission research facility in Alaska jointly operated by the US Navy, Air Force and several universities; a BIG particle gun.
RCON is a text based protocol completely unrelated to the Source RCON protocol. It is designed with readability, ease of implementation, and human usability in mind.
RCON therefore only guarantees the reliability of character values [1, 127]. This is largely because RCON is interpreted entirely as strings by the Renegade X server, but both TCPLink and Rx_TCPLink are incapable of directly reading or transmitting non-ASCII characters when in text mode.