  We describe a Fortran 90 program to calculate population ratios of atomic
levels. The program solves the equations of statistical equilibrium considering
all possible bound-bound processes: spontaneous, collisional or radiation
induced (the later either directly or by fluorescence). There is no limit on
the number of levels or in the number of processes that may be taken into
account. The program may find a wide range of applicability in astronomical
problems, such as interpreting fine-structure absorption lines or collisionally
excited emission lines (such as coronal emission lines) in the spectra of
several objects, and also in calculating the cooling rates due to collisional
excitation.
