This obsolete value used to select whether data transmitted on the FT1 interface was sent in normal or inverted polarity, with inversion historically used with certain line coding schemes to guarantee enough one's density for clock recovery at the far end. Because the object is marked obsolete, an admin encountering it today should treat it as legacy configuration rather than something to actively manage on current equipment. For example, an old FT1 deployment relying on AMI line coding without B8ZS might once have set this to inverted(1) to maintain adequate signal transitions.