“…If ψ : S * −→ C 3 is given by osculation then it is null. Let ζ be an affine coordinate on P 1 , giving the local coordinates (ζ, η) −→ (ζ, ηd/dζ ) on T. If the affine part of a curve S in T is described in these coordinates by a pair of meromorphic functions (g, f ) on a Riemann surface M, then, with respect to a certain choice of basis for H 0 (P 1 , O(T)) [11], the coordinate functions of the auxiliary null curve ψ : M * −→ C 3 are given by the Weierstrass formulae (1)-(3). Now, Q 0 = C(Q 1 ) fixes a point in P 9 , the space parameterising all quadrics in P 3 .…”