Field I/O: The wires a gateway actually has: framed serial packets, an RS485 request and the reply it draws, a CAN frame, the address a chip answers on, and the bus that carries a driver to the part.
Profiles and robotics: A node written down as a JSON file, rules between nodes as another, and the naming and encoding rules a robot's topics follow, with no ROS 2 or Zenoh installed.
Radio and reach: Budgeting airtime, framing a mesh packet, routing it, and securing a LoRaWAN uplink: everything a node needs to reach a network it cannot see.
Sensing and actuation: The parts wired to a board: a thermometer that checks its own bytes, a servo pulse, a stepper walking its coils, and a part of your own.