(a) Comparison of ${\rm d}N_{\gamma}/{\rm d}\eta_{\rm lab}$ measured at forward rapidity in INEL pp collisions for various center-of-mass energies, (b) average photon multiplicity within 2.3 $< \eta_{\rm lab} <$ 3.9 as a function of collision energy in INEL pp collisions. The results at 0.9, 2.76, and 7 TeV are taken from Ref. .