  When does a GRB stop and its afterglow begin? A GRB may be defined as
emission by internal shocks and its afterglow as emission by an external shock,
but it is necessary to distinguish them observationally. With these definitions
irregularly varying emission (at any frequency) must be the GRB, but smoothly
varying intensity is usually afterglow. The GRB itself and its afterglow may
overlap in time and in frequency, and distinguishing them will, in general,
require detailed modeling.
