/**
 * The letters a character stands for, for a character nothing can draw.
 *
 * @param cp The code point.
 * @returns The letters, or `undefined` when the character is a letter itself.
 */
export declare function substituteLetters(cp: number): string | undefined;
/** Whether any code point of `text` is one {@link substituteLetters} answers for. */
export declare function hasSubstitutable(text: string): boolean;
/**
 * The letters a LIGATURE stands for, for the one place that asks only about
 * those: the `/ToUnicode` a drawn ligature glyph is stated by.
 *
 * @param cp The code point.
 * @returns The letters, or `undefined` when it is not one of these ligatures.
 */
export declare function lettersForLigature(cp: number): string | undefined;