  The nebular spectra of the broad-lined, SN 1998bw-like Type Ic SN 2002ap are
studied by means of synthetic spectra. Two different modelling techniques are
employed. In one technique, the SN ejecta are treated as a single zone, while
in the other a density and abundance distribution in velocity is used from an
explosion model. In both cases, heating caused by gamma-ray and positron
deposition is computed (in the latter case using a Monte Carlo technique to
describe the propagation of gamma-rays and positrons), as is cooling via
forbidden-line emission. The results are compared, and although general
agreement is found, the stratified models are shown to reproduce the observed
line profiles much more accurately than the single-zone model. The explosion
produced ~ 0.1 Msun of 56Ni. The distribution in velocity of the various
elements is in agreement with that obtained from the early-time models, which
indicated an ejected mass of ~ 2.5 Msun with a kinetic energy of 4 x 10^{51}
erg. Nebular spectroscopy confirms that most of the ejected mass (~ 1.2 Msun)
was oxygen. The presence of an oxygen-rich inner core, combined with that of
56Ni at high velocities as deduced from early-time models, suggests that the
explosion was asymmetric, especially in the inner part.
