  We present the main observational features expected for GRBs that occur
inside pulsar wind bubbles (PWBs). This is the most natural outcome of
supranova model where initially a supernova explosion takes place, leaving a
supra-massive NS, which loses its rotational energy over a time t_sd and
collapses to a BH, triggering a GRB explosion. We find that the time delay t_sd
between the supernova and GRB events is the most important parameter that
determines the behavior of the system. We consider the afterglow, prompt GRB
and direct emission from the PWB. The observational signatures for different
t_sd are described and joined together into one coherent framework. Constraints
on the model are derived for a spherical PWB, from the lack of detection of the
PWB emission and afterglow observations. For very low values of t_sd<1 hr the
supranova model reduces to the collapsar model; 0.4<t_sd/1yr<1 is required to
produce the iron lines seen in some X-ray afterglows. However, we find that for
a spherical PWB, this implies no detectable radio afterglow, a small jet break
time and non-relativistic transition time, in disagreement with observations
for some of these GRBs. These discrepancies with the observations may be
reconciled by resorting to a non-spherical geometry. We find that light element
lines, recently detected in a few X-ray afterglows, are expected to dominate
over iron lines for small t_sd, while for large t_sd the situation is reversed.
Finally, we predict that external Compton scattering of the PWB photons by the
afterglow relativistic electrons, should lead to high energy emission during
the early afterglow that may explain the GeV photons detected by EGRET in some
GRBs, and should be detectable by future missions (GLAST).
