(C1) Orientation constraint. There are up to 6 box orientations
possible, but only 3 vertical box orientations. For certain box
types, up to 2 of the maximal 3 possible vertical orientations are
prohibited.
(C2) Support constraint. The bottom of each box which is not
placed on the floor of the container must be supported
completely (i.e., 100%) by other boxes underneath.
(C3) Guillotine cutting constraint. All boxes in a packing plan can
be reproduced by a series of guillotine cuts. The cutting area of a
guillotine cut lies parallel to a boundary surface of the container,
and the cut piece is always completely separated in
two smaller parts.