This read-only object reports what the ifIndex of this stacking port will be, or become, after a reset, as opposed to its current live ifIndex. An admin planning a reboot-driven interface renumbering can use this to know in advance what ifIndex to expect for scripts or monitoring configuration that reference stacking ports by number. For example, before rebooting a stack that is about to have its trunk membership changed, the admin checks this field to update monitoring templates with the ifIndex that will apply once the reset takes effect.