  (Pseudo) radiative pumprate of OH 1612 MHz masers is defined for a sample of
44 OH/IR sources (infrared sources with OH 1612 MHz maser), irrespective of the
real maser pumping mechanisms. The correlation between the (pseudo) maser
pumprates and the evolutionary status of the maser sources reveals that the
radiative pumprates of stellar OH masers are nearly fixed, which agrees with
the theoretical prediction for radiatively pumped OH maser. The (pseudo)
radiative pumprates of interstellar OH masers are not only very small but also
varying broadly over two orders of magnitude, which is argued to be the
manifestation of varying number of quiet absorbing OH cloudlets and/or various
OH maser pumping mechanisms and/or competitive gain between mainline and 1612
MHz OH masers and/or anisotropy of the maser emission. The radiative pumprates
of post-AGB OH masers very possibly decrease with increasing IRAS C32 color
indices and distribute in an interim region between the stellar and
interstellar OH masers in the pumprate-color diagram.
