The «resonating valence bond» (RVB) state has been proposed as the basis for an explanation of high-temperature superconductivity. Recently, we have described the charge and spin excitations about this state, and have shown that they are solitons, precisely analogous to those found in polyacetylene. Since the charged solitons are + e bosons, it is natural to ask whether flux quantization will occur in units of hc/2e, as in traditional BCS superconductivity, or will come only in larger units of hc/e. We show here that flux quantization in units of hc/2e will occur unless a condensation of cooperative ring exchanges occurs analogous to that found in the fractional quantized Hall effect. © 1988 IOP Publishing Ltd.