* *meter-in* and *meter-out* are XBus inputs and outputs that connect this node to a building’s “smart grid” power meter.
* *lower-in* and *lower-out* are XBus inputs and outputs that connect this node to a node with a lower ID number.
* *higher-in* and *higher-out* are XBus inputs and outputs that connect this node to a node with a higher ID number.
* The first value in a data packet is the ID number of the destination, and indicates how the packet should be handled:

##############

|   ID < meter ID   | retransmit data packet to the lower node
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|   ID = meter ID   | retransmit data packet to the meter
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|   ID > meter ID   | retransmit data packet to the higher node

* The local ID number of the node is stored in a secure identity chip that can be read as an XBus input.
* The second value in a data packet is the length of the rest of the data packet.