 the standard one formula_1), then a Dirac structure is a maximally isotropic integrable vector subbundle "L → M", i.e.As discovered by Courant and parallel by Dorfman, the graph of a 2-form "ω" ∈ "Ω"2("M") is maximally isotropic and moreover integrable iff d"ω" = 0, i.e.the 2-form is closed under the de Rham differential, i.e.