Container

What parts are stacked on, or into.

Pallets

The usual container: a footprint, a height, and a position in the cell. The recipe computes every drop position from the container, so its dimensions have to be the real ones.

A cell normally has one or two container positions — the stations an operator loads and unloads.

Boxes

Palletising into a box rather than onto a pallet is on the roadmap.

Interlayers

A sheet placed between layers. Where the recipe uses them, it needs to know their thickness: an interlayer that is not declared makes every layer above it land slightly low, and the error accumulates up the stack.