"A LoRaWAN network has a short network identifier ("NwkID") which is a seven bit value. If a network wishes to support "foreign" end-devices then the NwkID needs to be registered with the LoRA Alliance, in which case the NwkID is the seven least significant bits of a registered 24-bit NetID. NetID starting with '00' or '01' are usually intended for private networks and experimental nodes.".
Valid examples: "00B2A1", "00C3D2", "0009C7"