BLANK can be performed by any group of instruments of which at least two must be able to sustain sounds for up to 40 seconds. The distribution of the three lines of music between the instruments should be such that each line is equally audible. Amplification may be used to enhance the fusion of the ensemble sound. Intervallic relationships in BLANK are based on Pythagorean intonation. The chart below shows the pitch interrelationships used. Where two different frequencies are given for the same note name, the lower pitch is notated in the score as a black notehead, the higher pitch as a white notehead.