Cornice designs and structures are manifold, though common to all is that the cornice’s centre of gravity should lie vertically above the underlying and supporting masonry.
The cornice shown in the figure also occurs without a plaster coat, just as the opposite may be the case where the profile is continuous.
Recommended literature in Danish:
Herholdt: Vejledning i Husbygningskunst (1877)
Danskbyggeskik.dk: Bygningsdel/tage og tagværker