  We report on a study of the gamma-ray continuum emission from the Crab
supernova nebula and on a search for nuclear de-excitation gamma-ray lines.
Crab is the brightest continuum source in the 1-10 MeV gamma-ray sky, and its
continuum radiation is most likely of synchrotron origin. It is a likely source
of cosmic rays through shock acceleration and thus a potential candidate for
gamma-ray line emission from nuclear interactions. Five years of COMPTEL
observations enable a fine spectral binning to investigate the behaviour of the
0.75-30 MeV emission in detail and to search for nuclear de-excitation lines on
top of the continuum. The nebular spectrum shows a break at the edge of the
COMPTEL energy range and connects well to the EGRET spectrum, probably
reflecting electron energy losses in the synchrotron emission scenario. Such a
smooth continuum model alone may not be sufficient to explain the observations.
A weak bump in the spectrum at 1-2 MeV may be present. No significant evidence
for distinct line emission is seen, but the presence of a blend of line
features or another synchrotron component cannot be excluded.
