There are two remedies of this problem, both of which uses digraphs for the letters with diacritics. Zamenhof, the inventor of Esperanto, an "h-system", which replaces "ĉ, ĝ, ĥ, ĵ, ŝ," and "ŭ" with "ch, gh, hh, jh, sh," and "u," respectively. A more recent "x-system" has also been used, which replaces "ĉ, ĝ, ĥ, ĵ, ŝ," and "ŭ" with "cx, gx, hx, jx, sx," and "ux," respectively.