You cant pin it down because both the Z136 and EN207/208 specifications are for sale to those who wish to purchase them. You can find bits here and there but you will not find the complete specifications without purchasing them.
For EN207 they take sample of the filter and subject them at 10cm to CW and pulsed lasers across the wavelengths the filter is to be certified for. The testers keep turning up the power until the lens is breached. The highest power the filter can withstand for 10 seconds sets the rating. Transmitted energy is also measured and weighed against the standard within that 10 second time frame. For pulsed lasers it's 100 pulses per test. They test giant pulses, q-switched pulses and mode locked short pulses as those are figured into the ratings also. Those make up the DIRM ratings you see on the filters such as D 532nm L5, or M 532nm L2.
