  We provided separate bivariate log-normal distribution fits to the BATSE
short and long burst samples using the durations and fluences. We show that
these fits present an evidence for a power-law dependence between the fluence
and the duration, with a statistically significant different index for the long
and short groups. We argue that the effect is probably real, and the two
subgroups are different physical phenomena. This may provide a potentially
useful constraint for models of long and short bursts.
