Hal in Tavis's waiting room (p. 513)
Lateral Alice Moore's desk's chair's wheels fit on a track with an electrified third rail, so she can slide from one corner of the horseshoe's arc to the other—more or less laterally—at the touch of a cerise desktop button.
Context
Lateral Alice Moore lives on the arc of her horseshoe desk — a life constrained to a partial ring (and it's this desk Hal's orbit will round at p. 523).