This paper offers a provisional mathematical typology of metrical representations. First, a family of algebras corresponding to different versions of grid and bracketed grid theory is introduced. It is subsequently shown in what way bracketed grid theory differs from metrical theories using trees. Finally, we show that there are no significant differences between the formalism of bracketed grids (for metrical structure) and the representation used in the work of [Kaye, et al., 1985], [1990] for subsyllabic structure. .
