This looks like a way to allow for addressing nodes on a CAN, RS485 or DMX network without needing to use either DIP switches or PCB changes.
Swarmbot
2 posts
The Arduino Compatible Pro Micro and the Arduino Leonardo both use the ATmega32u4, which has built-in USB communications. While this eliminates the need for a secondary processor or UART chip, it allows the Leonardo to appear to a connected computer as a USB device, such as a mouse or keyboard, […]