Panel a: X-ray spectrum of 4U 1901+03 collected during NuObs3 together with the two-component models TBABS × (GAU + COMPTT + COMPTT × GABS) and TBABS × (GAU + PO × HIGHECUT + PO × HIGHECUT × GABS) where the corresponding model components are shown by the dashed curves in red and blue, respectively. Panel b: residuals for the former composite model (COMPTT). Panel c: residuals for the latter composite model (PO×HIGHECUT). The color code is same as for Fig. 2.