export declare const BOOKLET_UNKNOWN_DATE_EN = "Unknown date";
/** Year-only date (optional GEDCOM qualifier). */
export declare function isYearOnlyDate(dateLabel: string): boolean;
/** "on 15 March 1991", "in 1991", "about 1700", "before 1800", etc. */
export declare function onDate(dateLabel: string): string;
/** "From 1700 to 1850" or "From 15 March 1700 to 3 January 1850". */
export declare function lifeDateRange(from: string, to: string): string;
/** "was born in 1991" or "was born on 15 March 1991". */
export declare function seesDayOn(dateLabel: string): string;