My "story" isn't what some other guy posts.
I'm responding to you. Not others.
Zero is no attenuation loss.
Atmospheric numbers are linked here:
http://www.freespaceoptic.com/WhitePapers/Comparison_Of_Beam_in_Fog.pdf
0.1 is an attenuation factor for 1.0km in clear sky.
or, 0.0001 for one meter in clear sky.
Sorry but I can't respond as I'm not sure to what the Moderator is objecting.