It’s ez - once you know it’s an “overhead fault indicator” ;)
It would have been a loooong time before I got that, if ever.
I would have never guessed it. Didn’t know such a thing even existed...
First thought was camera, but since I’m a long time photographer it only took a couple of seconds to rule that out. After that I was baffled...
Something like that does lend itself to some off the wall theories though...the flux capacitor post comes to mind...