Remarks on the Single-Photon Spectra from CERN-WA80

In this letter the author points out that in recent WA80 data an apparent slope parameter of T_exp ≈180 MeV/c must not mean the fireball becoming equilibrated in whole at some temperatures throughout the stages of the evolution. The author also demonstrates that T_exp is merely a mean value of the temperatures of various high-energy photon sources, and predicts that for higher colliding energies (> 200 A GeV) the shape of the measured single-photon spectra would exhibit some concave curvature, which may be used as a probe for diagnosing quark-gluon plasma.