Originally Posted by
ScottBouch
Thank you! Yes, this is of retrospective interest / research!
So the remaining question is can anyone find what the initials "FI" stand for?
I'm tempted to make an obvious assumption here, but am going to put that aside in anticipation of correct confirmation, as we all know what ASSUME stands for!
Many thanks, Scott.
Could well be F-L, my exaggeration, to describe a flashing light. That's certainly how light houses (those that were flashing not occulting) were annotated, though those included the flash pattern.