usdERXSysSlotAssociatedSlot 1.3.6.1.4.1.4874.2.2.17.1.4.2.1.18

If the module is a primary card and the spare is acting on its behalf, then the value of this object is the slot number of the associated spare. If the module is a primary card and is active (not spared), then the value of this object is the cards actual slot number. If the module is a spare card and it is active, then the value of this object is the slot number of the primary card that is being spared for. If the module is a spare and it is inactive, then the value of this object is the its own slot number. If module is not part of a redundancy group, or the slot is empty, the value of this object is 255.