According to Bob Gilmore the piece, "take[s] extended just intonation well beyond the point reached by Harry Partch.
"[1] "The piano is tuned to a selection of overtones from the fifth octave of the harmonic spectrum of C. All octaves are tuned in the same scale....The lowest C (33 Hz.)
"[2] Alarum is a Shakespeare era stage direction indicating "a grand entrance" and an archaic word for a call to arms, so "Alarum" is a fanfare.
"Etude" is a study in serial technique and six-against-five polyrhythms in which Johnston indicates "blur with pedal".
This, "clues us in that the linear intricacies are only part of the story here: the amazing swirl of overtones resulting from an atonal application of this tuning are of equal importance.