N3_sub/libraries/AP_UAVCAN/dsdl/ardupilot/README.md

This directory contains the DSDL for the ArduPilot vendor specific UAVCAN messages.

For service messages we use IDs starting at 200

For non-service messages we use IDs starting at 20000

https://uavcan.org/Specification/5._Application_level_conventions/#id-distribution