Transversity of a massless relativistic membrane

We consider the relativistic theory of the open two-dimensional surface which is characterized by an action proportional to the volume swept out by the surface in spacetime. It is shown that classically there are only D−3 dynamically independent transverse components among the D functions X^∓ (σ₁, σ₂, τ) which represent the world volume (D is the dimension of spacetime) and that the surface boundary moves with the velocity of light.