This paper introduces the new audiovisual sequencing system "Versum" that allows users to compose in three dimensions. In the present paper the conceptual soil from which this system has sprung is discussed first. Secondly, the basic concepts with which Versum operates are explained, providing a general idea of what is meant by sequencing in three dimensions and explaining what compositions made in Versum can look and sound like. Thirdly, the practical ways in which a composer can use Versum to make his own audiovisual compositions are presented by means of a more detailed description of the different graphical user interface elements. Fourthly, a short description is given of the modular structure of the software underlying Versum. Finally, several foresights regarding the directions in which Versum will continue to develop in the near future are presented.