Definitions of current components used in data analysis. (A) Contribution of the constant (I_B) and flickering components (I_app) of each pore to the measured single-porin current. (B) Illustration of the levels I₀ to I₃ observable in a measured time series. (C) Scenario used for fitting amplitude histograms. I_p is the sum of I_B and the true (reconstructed by fitting) single-pore current I_true.