This defines the visual gap, as a layout string, inserted between groups of slots along the array's secondary ('transverse') axis, perpendicular to the primary slot direction. Where inlineGroupSeparation groups slots within a row, this value groups whole rows of slots relative to each other, reproducing multi-row bay layouts that have a visible divider between rows rather than one evenly-spaced grid. A value like '6' leaves a slightly larger visual gap between the top and bottom row of a two-row, 24-bay front panel.