simpl ⚬ˣˢᵖᵉᶜ｜appendage｜___｜20260628155835-01-•

A	B
par1	Gamma, the photon power law index.
par2	The scattered fraction (between 0 and 1).
par3	A flag to switch between up-scattering only ($>0$) and both up- and down-scattering ($\le 0$)

(echo:: @ ᯤ)