Three tempi proceed simultaneously. Each instrument follows a series in one of the three basic tempi of the piece. Series and tempi can be exchanged between instruments, but the three basic tempi, in the original, divided, or augmented form, proceed parallel to one another during the entire composition. When the periods of the three different tempi land on the same pulse, a new "room" is opened. Rum is built from two series of numbers, 3 1 4 2 5 and 2 1 4 3 5, as well as their mirrored and retrograde variants. These series have been applied to the larger form, split into five parts according to the series 3 1 4 2 5; and to the rhythmic structure within a period of fifteen pulses (fifteen being the sum of a series).

Madeleine Isaksson (Translation : George Kentros)