export declare const TIMEZONES: string[];
/** Validates timezones with `Intl` to avoid alias mismatches like `Asia/Calcutta` vs `Asia/Kolkata`. */
export declare function isValidTimezone(zone: string | null | undefined): boolean;
/**
 * `Date.UTC` with the year taken literally. `Date.UTC(y, ...)` (and `new Date(y, ...)`) remap years 0-99 to 1900-1999,
 * so year 0001 silently becomes 1901. This anchors the same fields in UTC without that remap; for years >= 100
 * it returns exactly what `Date.UTC` returns, overflowing month/day/time fields included.
 */
export declare function utcFromFields(year: number, month0: number, day?: number, hours?: number, minutes?: number, seconds?: number, ms?: number): number;
/**
 * Whether a clock face reads as a real time of day. Hours 0-23, minutes and seconds 0-59; `24:00:00(.000)` is ISO 8601
 * end-of-day and is kept (it resolves to the next midnight). Anything else, e.g. 25:61:00, is not a time: date math would
 * silently roll it into the next day, so callers treat the value as unparseable instead.
 */
export declare function isClockTime(hours: number, minutes: number, seconds?: number, ms?: number): boolean;
/** Host-local counterpart of {@link utcFromFields}: `new Date(y, m, d, …)` remaps years 0-99 to 1900-1999, this does not. */
export declare function localDateFromFields(year: number, month0: number, day?: number, hours?: number, minutes?: number, seconds?: number, ms?: number): Date;
/** Fallback year range when `startYear` / `endYear` are not set: the year dropdown, and in the date-time-picker variant also month navigation and typed-year clamping. An explicit bound always wins. */
export declare const DEFAULT_START_YEAR = 2000;
export declare const DEFAULT_END_YEAR = 2050;
/** Four-digit year for `YYYY` tokens: years 0-99 are zero-padded (`0050`); every other year renders exactly as `String(year)`. */
export declare function formatYear4(year: number): string;