  The radiation process of GRB prompt emission remains highly debated till
date. Though a smoothly broken powerlaw function like Band provides an
excellent fit to most of the cases, a spectrum with a broad top or double hump
structure has emerged recently for several GRBs, specifically for the bright
ones that have high signal to noise data. A number of models have been proposed
to capture this shape which includes an additional blackbody component along
with the Band, or a double smoothly broken powerlaw, or two blackbodies with a
powerlaw/cut-off powerlaw and so on. However, finding the statistically
favourable model has not always been possible primarily due to the limited
resolution of GRB detectors. Recently, we have identified a number of
interesting cases where an observation with focusing detectors are available at
a later part of the prompt emission. Their high resolution data helped in
identifying additional spectral component (a blackbody) in lower energies. The
proposed THESEUS mission, with its unprecedented sensitivity and spectral
resolution available from the very beginning of the prompt emission holds the
key to identify the correct spectral model and thereby the radiation process.
