The instance IDs that are associated with the draw commands.
Unity only uses this command when it renders object-picking data in the Editor, which is when BatchCullingContext.viewType is equal to BatchCullingViewType.Picking. Otherwise, Unity ignores this value and you can leave it set tonull. Each element in this array corresponds to the draw command with the same index in the BatchCullingOutputDrawCommands.drawCommands array. Both of these arrays must therefore be the same size.
See Also: BatchRendererGroup.SetPickingMaterial.