An example of a two-dimensional zone is the QMI layout with the forward pick zones on the right side of storage and pallet (reserve) storage zone on the left. A three-dimensional zone has picking locations on the lower level racks with pallet reserve storage overhead.

In the graphic above, the picture on the left is an example of a two-dimensional zone similar to the QMI layout. All locations in the entire rack are in the same zone.

On the right, a three-dimensional zone might have bulk/pallet storage zone locations on the top sections, and box or each locations on the bottom, floor-accessible sections.