Light is a loan with interest. Museums cap both instant lux and lux-hours per year. Pick a material class, the gallery level and the hours the case is lit. The plaque says whether the year is still in credit.
Bands follow the CIE / IES / AIC museum-lighting consensus used in UK and US conservation teaching (50 / 150–200 / 300 lx). Annual budgets of ~50,000 and ~150,000 lux-hours are the usual teaching figures. UV should be filtered separately; this hall only counts visible lux. Not a facilities specification.