/**
 * Return the symmetric difference of two Unix intervals — time covered by exactly one interval.
 *
 * - Compares numeric Unix epoch values directly.
 * - Returns `[]` when intervals are identical or both invalid.
 * - Returns `[{ start, end }]` when one interval fully contains the other.
 * - Returns `[{ start, end }, { start, end }]` when intervals partially overlap.
 * - Returns `[]` if either interval is invalid (`start > end`).
 * - Returns `[]` on invalid input (non-numeric types, non-finite values).
 *
 * @param aStart Unix epoch value (seconds or milliseconds) — first interval start
 * @param aEnd Unix epoch value (seconds or milliseconds) — first interval end
 * @param bStart Unix epoch value (seconds or milliseconds) — second interval start
 * @param bEnd Unix epoch value (seconds or milliseconds) — second interval end
 * @returns array of `{ start, end }` records representing the symmetric difference, or `[]` on invalid input
 *
 * @example intervalXorUnix(0, 1500000000, 1400000000, 1700000000) // [{ start: 0, end: 1399999999 }, { start: 1500000001, end: 1700000000 }]
 * @example intervalXorUnix(0, 1700000000, 1400000000, 1500000000) // [{ start: 0, end: 1399999999 }, { start: 1500000001, end: 1700000000 }]
 * @example intervalXorUnix(0, 1700000000, 0, 1700000000) // []
 * @example intervalXorUnix(NaN, 1500000000, 1400000000, 1700000000) // []
 */
export declare function intervalXorUnix(aStart: number | string, aEnd: number | string, bStart: number | string, bEnd: number | string): Array<{
    start: number;
    end: number;
}>;