Dold proved that a
homomorphism ϕ : Hn(BO) → ℤ2 corresponds to a manifold Mn if and
only if ϕ(Sqpu + vp⋅ u) = 0,∀p ≥ 0 and ∀u ∈ Hn−p(BO), vp being the
Wu class. The object of the present work is to have a singular analogue of
this result and to study the bordism classification of singular manifolds in
BO.