Redundancy in Nonlinear Programs

A stackable shelf unit is disclosed which is adapted to be stacked and supported upon a like shelf unit. The shelf unit is preferably fabricated from plastic coated metal wire, and includes a pair of spaced side frame members between which extend a plurality of spaced shelf members. The side frame members each include a pair of downwardly depending leg portions, with each leg portion including an offset portion adapted to engage and be supported upon the like shelf unit so that the shelf unit may be stacked thereupon.