In contemporary music discourse, form is defined as the overall structure of a concert work, the ‘constructive organising element’ (Whitall 2014) that
‘[governs] the presentation, development, and interrelationship of [musical] ideas’ (Owens 2014)

form generally accounts for the ‘disposition of certain structural units successively in time’, or the ways in which materials or ‘musical structure’ are ‘put together’ (Whitall 2014; Kirby 2013).

While most works involve spatially distributed sonic materials that unfold in time, these ‘energetic’ media architectures (Sterken 2001: 263) are
encountered by a mobile visitor within a userdetermined temporal frame. That is, in opposition to the concert work, installations (1) lack formalised or `sanctioned’ material vocabulary and often involve (2) the ‘literal presence … [of a mobile] … embodied [visitor]’ (Bishop 2005: 6). The latter aspect in particular limits the artist’s control of (3) the temporal frame (start and ending point, as well as duration of exposure), and (4) the focus and position of the audience, who are often not presented with a (5) privileged
viewing or listening position.

The installation artist Olafur Eliasson posits that in his time-based installations (as well as everyday spatial experience), the three Euclidian dimensions (length, width and height) are not only modulated by the fourth, topological dimension (time), but also by the fifth ‘dimension’ of subjectivity: YourEngagement Sequence (or YES), the first-person sequential unfolding of four-dimensional experience (Eliasson 2006: 62–7). This relational engagement, which inscribes the former four dimensions with a ‘ softness through negotiation … is only possible whenthe fourth dimension present; without a notion oftemporality the idea of engagement does not make sense’ (Eliasson 2006: 66).