  The luminosity and the spectral distribution of the afterglow of GRB 031203
have been presented within our theoretical framework, which envisages the GRB
structure as composed by a proper-GRB, emitted at the transparency of an
electron-positron plasma with suitable baryon loading, and an afterglow
comprising the "prompt emission" as due to external shocks. In addition to the
GRB emission, there appears to be a prolonged soft X-Ray emission lasting for
10^6-10^7 seconds followed by an exponential decay. This additional source has
been called by us URCA-3. It is urgent to establish if this component is
related to the GRB or to the Supernova (SN). In this second case, there are two
possibilities: either the interaction of the SN ejecta with the interstellar
medium or, possibly, the cooling of a young neutron star formed in the SN
2003lw process. The analogies and the differences between this triptych GRB
031203 / SN 2003lw / URCA-3 and the corresponding ones GRB 980425 / SN 1998bw /
URCA-1 and GRB 030329 / SN 2003dh / URCA-2, as well as GRB 060218 / SN 2006aj
are discussed.
