The other aspect is seen in the presence of a quadratic form Q on V ; if it is non-degenerate it allows an identification of the dual space V of V with V. The relation of V to V is not intrinsic; it depends on a choice of Haar measure (volume element) on V. But given an identification of the two, which is in any case well-defined up to a scalar, the presence of Q allows one to speak to the dual lattice to L while staying within V.