Intrinsic period-lattice conjecture for analytic K3 surfaces

Let $K={{\bf C}}((t))$ and let $X^{an}/K$ be an analytic K3 surface admitting an analytic torus fibration $X^{an}\to S^2$ with standard singularities. Intrinsic period-lattice conjecture. One can define intrinsically a lattice $\Lambda_{X^{an}}$ and a homomorphism $\rho_{X^{an}}:\Lambda_{X^{an}}\to K^\times$. The conjecture proposes that these structures are determined intrinsically by the analytic K3 surface together with its standard-singularity torus fibration; the source gives no general construction or proof.