export declare function useBackdatePo(controller: {
    getEffectiveAt(): FdoPurchaseOrder['effectiveAt'];
    setEffectiveAt(effectiveAt: FdoPurchaseOrder['effectiveAt']): void;
}): {
    backdatePo: import("vue").WritableComputedRef<Date | null, Date | null>;
    backdateSwitch: import("vue").WritableComputedRef<boolean, boolean>;
    backdateModel: import("vue").WritableComputedRef<"" | `${string}-${string}-${string}`, "" | `${string}-${string}-${string}`>;
    backdateTimeModel: import("vue").WritableComputedRef<"" | `${string}:${string}`, "" | `${string}:${string}`>;
};