J'ai posté aussi cette question sur le forum Eventide et voici la réponse d'un des concepteurs (Leon) : once a tone row is playing and you are on the play mode screen (where you may see “PRIME” at top left), then press/hold user 4 (“+”) and press the UNDO key (⎌). At first this will just play the tone row at half speed, basically, but as you add other intervals to the interval sequence (press/hold user 4 (“+”) and press the interval buttons (“+1”, etc)), you can get that rest to appear only occasionally.