This is the slot identifier, per CucsFabricBreakoutSlotId, indicating which expansion module or fixed slot on the fabric interconnect contains the port this breakout configuration applies to. On larger fabric interconnects with multiple expansion modules, this field on this specific row is necessary, together with portId, to physically locate the correct port, since the same port number can exist in more than one slot. A slotId of '1' paired with a portId of '32' identifies port 32 specifically on the module installed in slot 1, distinct from a same-numbered port in a different slot.