Measure and report the spectral power distribution of the acute stimulus from the observer’s point of view at a known and specified angle and distance from the source Measure and report the spectral power distribution of the background light environment from the observer’s point of view at a known and specified angle and distance from the source Make spectra available in tabulated form Report α-opic (ir)radiances and illuminance Describe the timing properties of stimulus (clock time, duration and pattern) Describe the spatial properties of stimulus (spatial arrangement and extent) Report measurement conditions and equipment