On Tue, 01 Nov 2016 09:08:01 -0700, Jeff Liebermann wrote:

LM-40 = time for 50% of the lamps in a large group to burn out

One more. ARL:
http://www.bulbs.com/learning/arl.aspx
"Average Rated Life (ARL) is how long it takes for half
the light bulbs in a test batch to fail"
I seem to recall others, but I'm too lazy to Google.

I remember reading in your prior reference that the time for half to fail
isn't useful for LEDs though, since they fail differently.