Electromagnetic Single Scatter (__SS) Option

Hi!

I was curious to find more information on how exactly the optional single scatter suffix __SS when specifiying EM processes works? Am I correct in assuming it just kills any tracks of anything that is scattered >1 times, or is there more nuance to it? I am struggling to find any useful documentation on how it works so any pointers to information/information anyone may have on this would be appreciated!!

Lauryn