Right now there is no self-calibration feature in the meter. It’s calibrated against external references in the factory and the calibration data is saved to flash. Right now the best way for a user to verify that the meter is in-spec is to measure an external reference with it.
User calibration is another feature on the firmware to-do list, but I think it will still be a few months before I can get to it :)
If you’re curious about the factory calibration, it has a few precision sources:
Let me know what other information I can provide. Best