DLP7000UV: Damage threshold intensity with peak @ 365 nm and tails going below 363 nm

The spec sheet for DLP7000UV & DLP9500UV says the damage threshold is 2.5W/cm2 from 363-400 nm and the threshold drops suddenly to 2 mW/cm2 below 363 nm. I was wondering if the damage threshold drop is sudden (like a cliff) or more like a gradual drop (over 20-40nm). The window transmittance curve shows a gradual decrease in transmittance and not a sudden reduction by 3 orders of magnitude (http://www.ti.com/lit/ds/symlink/dlp7000uv.pdf). 

I would assume the objective of this damage threshold from 363-400 nm is to capture the 365 nm peak of typical UV lamp spectrum (its tails go below 365 nm). So, if using a mercury lamp source with 365 nm peak & some tail below 363nm, these DMDs should still be okay upto 2.5 W/cm2 ? Is my assumption correct ? Or the tail (< 363 nm) of the 365nm lamp peak would damage the DMD if intensity goes above > 2mW/cm2 or how much degradation in life should we expect. Any clarifications/ variation of life with intensity & wavelengths plots etc. would be helpful.

Thanks,

Nilabh