Constant MAX_REPORTABLE_MLUX 

pub const MAX_REPORTABLE_MLUX: u32 = _; // 253_575u32

The largest value this board can report — the reading at SATURATION_RAW, about 253 lux.

A ceiling, not a measurement: everything from a bright room to direct sunlight lands on it. The part is a dark-end instrument, and at the dark end it is a good one — one count is 21 mlux, so full moonlight (~300 mlux) sits about 15 counts up with a 4 mlux noise floor beneath it. Anything wanting a daylight figure needs a different sensor.