HIST2LIMITS returns the threshold for detecting saturation artifacts. Saturation thresholds can be obtained from the histogram . This routine tries to obtain the saturation threshold in an automated way. The routine was tested with the histograms of 528 recordings with three respiratory channels each. Reference(s):  A. Schl�l, B. Kemp, T. Penzel, D. Kunz, S.-L. Himanen,A. V�ri, G. Dorffner, G. Pfurtscheller. Quality Control of polysomnographic Sleep Data by Histogram and Entropy Analysis. Clin. Neurophysiol. 1999, Dec; 110(12): 2165 - 2170.