This piece was written to test the Vienna Symphonic Library (VSL) Prepared Piano sample library from the Special Keyboards Library (that also comes with Harpsichord and Harmonium sample sets). There are a number of key-switched sound sets you can move between by playing a few very high notes out of the piano's playing range (the cue notes in the score are the key-switches which are not heard and change the prepared piano sample set when played). The piece is intended for computer performance only. One of the nice things about prepared piano is that it becomes a true percussion instrument at times and some of that is brought out in the piece. The VSL key-switched patches are triggered by:

C7 - Notes are played with a metal chain placed on the strings.
C#7 - Screws are inserted between the strings.
D7 - Harmonics are created damping the string with a finger.
D#7 - Harmonic Secco - the finger pressure is so strong that the string is not allowed to vibrate freely.
E7 - Notes are played with aluminum foil put on the strings.
F7 - A waterglass is placed on the strings to create this effect.
F#7 - Played directly on the strings with a drumstick: Single notes.
G7 - Played directly on the strings with a drumstick: Rolls.
G#7 - Glissandi played directly on strings (C4-A4: Up; C5-A5: Down).

Also note the VSL Prepared Piano patches also use MIDI velocity layer switching (0-88 for layer 1 and 89-127 for layer 2), except for the Harmonic patch (0-55, 56-127). The Stick and Harmonic secco patches only have one velocity layer. This is why there is a noticeable change in the sound in the piece for some patches as volume changes from piano to forte levels.