Ratio of the continuum X-ray fluxes at low state to Main-on state as a function of photon energy. A fluorescent iron line is not included. The dashed and solid lines show the calculated fraction of scattered X-ray radiation from the photosphere q_phot ∕q_x without and with taking into account the shadow from the disk, respectively. The gray area shows the observable (q′ + q_phot)∕q_x fraction withan addition of X-rays scattered in the corona (~0.01–0.02).