/**
 * Excel-compatible sheet name validation.
 *
 * Citations:
 * - Length ≤ 31 and uniqueness case-insensitive: [MS-OI29500] 2.1.578 sheet
 * - Forbidden base characters `' * [ ] \ : / ?`: [MS-XLSX] sheet-name-base-character
 *
 * @private
 */
/** Maximum sheet name length (Excel / [MS-OI29500]). */
export declare const MAX_SHEET_NAME_LENGTH = 31;
/**
 * Validate a proposed sheet name. Throws {@link InvalidSheetNameError} when illegal.
 */
export declare function validateSheetName(name: string): void;
/**
 * Case-insensitive sheet name equality (Excel uniqueness rule).
 */
export declare function sheetNamesEqual(a: string, b: string): boolean;
/**
 * Normalize for map keys: Unicode case-fold via lower-case.
 * Excel treats names as case-insensitive; locale-independent lower is sufficient.
 */
export declare function sheetNameKey(name: string): string;