/**
 * Returns midnight UTC for the provided date.
 */
export declare function startOfUtcDay(date: Date): Date;
/**
 * Adds seconds to a UTC date.
 */
export declare function addUtcSeconds(date: Date, seconds: number): Date;
/**
 * Adds minutes to a UTC date.
 */
export declare function addUtcMinutes(date: Date, minutes: number): Date;
/**
 * Adds hours to a UTC date.
 */
export declare function addUtcHours(date: Date, hours: number): Date;
/**
 * Adds whole UTC days to a date.
 */
export declare function addUtcDays(date: Date, days: number): Date;
/**
 * Adds whole UTC months to a date.
 */
export declare function addUtcMonths(date: Date, months: number): Date;
/**
 * Adds whole UTC years to a date.
 */
export declare function addUtcYears(date: Date, years: number): Date;
/**
 * Adds whole UTC months, or returns null if the target month has no such day
 * (e.g. adding 1 month to Jan 31 has no Feb 31) rather than rolling over into
 * the following month, per RFC5545.
 */
export declare function addUtcMonthsOrNull(date: Date, months: number): Date | null;
/**
 * Adds whole UTC years, or returns null if the target year has no such day
 * (e.g. adding 1 year to a Feb 29 DTSTART in a non-leap year) rather than
 * rolling over into March, per RFC5545.
 */
export declare function addUtcYearsOrNull(date: Date, years: number): Date | null;
/**
 * Applies the time portion from one UTC date onto another UTC day.
 */
export declare function applyUtcTime(day: Date, timeSource: Date): Date;