/** Canonical OOXML built-in number formats — verbatim from openpyxl. */
export declare const BUILTIN_FORMATS: Readonly<Record<number, string>>;
/** First numFmtId Excel reserves for user-defined formats. */
export declare const BUILTIN_FORMATS_MAX_SIZE = 164;
export declare const FORMAT_GENERAL = "General";
export declare const FORMAT_TEXT = "@";
export declare const FORMAT_NUMBER = "0";
export declare const FORMAT_NUMBER_00 = "0.00";
export declare const FORMAT_PERCENTAGE = "0%";
export declare const FORMAT_PERCENTAGE_00 = "0.00%";
export declare const FORMAT_DATE_DATETIME = "yyyy-mm-dd h:mm:ss";
export declare const FORMAT_DATE_TIMEDELTA = "[hh]:mm:ss";
export declare const FORMAT_DATE_YYYYMMDD2 = "yyyy-mm-dd";
/** Look up the format code for a given numFmtId, or `undefined` if unknown. */
export declare function builtinFormatCode(id: number): string | undefined;
/** Look up the numFmtId for a given format code, or `undefined` if not built-in. */
export declare function builtinFormatId(code: string): number | undefined;
/** True iff `code` is one of the OOXML built-in format strings. */
export declare function isBuiltinFormat(code: string): boolean;
/**
 * Heuristic: does the format string imply a date / time interpretation?
 * Looks at only the first format section (positive-value branch); strips
 * literals, colour codes and locale modifiers before scanning for date
 * tokens (d/m/h/y/s, case-insensitive) that aren't escaped.
 */
export declare function isDateFormat(code: string | undefined | null): boolean;
/** Heuristic: does the format string indicate a duration ([h]:mm:ss etc.)? */
export declare function isTimedeltaFormat(code: string | undefined | null): boolean;
/** Categorise a date format as 'date', 'time', 'datetime' or undefined. */
export declare function classifyDateFormat(code: string | undefined | null): 'date' | 'time' | 'datetime' | undefined;
export interface NumberFormat {
    /** Stylesheet-relative numFmtId. */
    readonly numFmtId: number;
    readonly formatCode: string;
}
export declare function makeNumberFormat(opts: {
    numFmtId: number;
    formatCode: string;
}): NumberFormat;