It stands for range knock-out floating rate note; a structured note (a floating-rate note) that provides the holder with higher interest payment (coupons) than an ordinary floating rate note but at the expense of suspension of interest payment for an entire period (usually one quarter) if the underlying reference rate slips outside the specified range for one day over the course of its lifetime.

By composition, this floating rate note consists of a vanilla floating rate note and a strip of embedded KO options (knock-out options).