This object reports the impedance setting for the external clock input on port 2 of the PXMUI-S3 back card, the second of two independently configurable timing input impedances on that back card. An admin cares because, just as with the primary port, a mismatch between this setting and the connected reference's actual impedance on port 2 specifically can introduce jitter or signal loss on that redundant timing path. For example, if port 2 is wired to a 100-ohm balanced T1 reference but this object is set for 75-ohm unbalanced, the backup timing feed will be unreliable even though the primary feed works fine.