GeO2-rich potassium borogermanate glasses are topologically complex, in that [BOn] (n = 3, 4) and [GeOn] (n = 4, 5, 6) polyhedra may all coexist. We wish to determine average Ge-O and B-O coordination numbers in these glasses by means of total diffraction, thereby estimating the equilibrium between the different network species as a function of composition. 11B NMR will complement this study and extend it over a wider region in composition space.