Abstract
This study is based upon 145 stars, from 04 to Al, whose spectra have or had at some time, one or more hydrogen lines in emission. They have been observed in two photometric systems: a') Johnson's HKL, b) Mendoza's (l6)A(9). The stars are divided in 5 working groups: 1) Wolf-Rayet stars, 2) Supergiant stars,3) Classical Be stars, 4) Peculiar Be stars, 5) Herbig Ae/Be stars. The photometric characteristics of each group are discussed. An outline of classification is given.
