I was wondering why some Esperantists use the x system (it isn't in the Esperanto alphabet) instead of h (which is in the Esperanto alphabet). Should not it be promoted to h, regularized, or something like that?

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    Probably because ‘x’ is not in the Esperanto alphabet, so there is never ambiguity. Commented Aug 20, 2020 at 5:52
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    Now I am wondering if you are asking this because of a misunderstanding. Neither the x nor the h are used as real letters, they are just used as an alternative to typing the letters ĥ ŝ ĝ ĉ ĵ and ŭ in cases where that is difficult. It wouldn’t make sense to consider x a letter of the alphabet any more than you would consider ^ a letter. It doesn’t have its own pronunciation.
    – Neil Roberts
    Commented Aug 20, 2020 at 8:57
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    'H' IS a letter in esperanto so there is the potential for ambiguity ('chashundo' could be 'ĉashundo' or 'ĉaŝundo'). Since 'x' isn't a letter there is no ambiguity. It's pretty simple. If you use 'h' you're adding ambiguity to a language intended to be free of ambiguity.
    – jastako
    Commented Sep 4, 2020 at 1:56

4 Answers 4


Two arguments I have encountered for preferring "x" to "h":

  • Because it is not an existing letter in the Esperanto alphabet, automated conversion is possible, e.g. sx could be unambiguously converted to ŝ. By contrast, even if combinations like -sh- are rare, they could occur in compound words e.g. dishaki, so sh cannot be reliably converted to ŝ (similarly senchava, flughaveno, etc).

  • Because it is so near the end of the alphabet, it is almost always the case that a naive lexical sorting will achieve correct alphabetical order. So for example, a naive sorting would put sxi after sorto (which would be correct, because ŝi comes after sorto), but would put shi before sorto. This only fails when a letter to which an accent could be applied is followed by z; for example a naive sort would misorder uxato (ŭato) and uzi, but such occurrences are very rare.

  • I always used the first point as explanation of why it's better to use x, but I see the second point is valid too.
    – apaderno
    Commented Apr 19, 2021 at 9:13

People tend to prefer the x-system exactly because it isn’t a letter in the Esperanto alphabet, so there is no risk of confusion. For example if you see the word flughaveno you might first ask yourself ‘what is a fluĝo?’ before recognising the word. With the X-system there is no such ambiguity.

These days the hats are pretty widely supported in browsers and most software, and it’s usually not too difficult to install some software to help type them, so both systems are less and less common.

  • It's actually so easy today, that a user who hasn't solved the issue for their device is often looked at with a pity. Commented Aug 20, 2020 at 12:03
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    The x-sistem is also more practical when alphabetizing a list in a computer, for example file names. Hatted letters always follow their plain siblings and x (unlike h) comes after most esperanto-letters in the English alphabet. Compare how segho/segxo is placed in a list with segilo. Commented Aug 21, 2020 at 17:22
  • @AntoniaMontaro, if you do that, you are alphabetizing Esperanto wrong. La ĉapelitaj letters are sorted separately i.e. first all c words, then all ĉ and so on. Commented Aug 24, 2020 at 9:30
  • @JuhaMetsäkallas I think alani's answer explains it in more detail. In most cases words will be correctly sorted.
    – marcus
    Commented Sep 8, 2020 at 14:40
  • "Most cases" is not enough ,say, for word list in a vocabulary. The alphabetical order should be unambiguous. See the project CLDR for exact alphabetical orders. Commented Sep 8, 2020 at 17:13

I personally prefer the more natural h (ch, sh) and such a notation was proposed as alternative for Esperanto letters. In the newer times the alternative with x was introduced with as argument: automatic translation. As chashundo was ambiguous chas-hundo. Try reta-vortaro.de with x's.

It is a subcultural phenomenon I think. Like accented characters are very dear to the language users. German without umlauts, a French café without accent droite, Spanish ñ. Even English borrowing façade.

Both are legal and understood. So use h with hyphens (chas-hundo) if it pleases. Meanwhile I am content to use x too.

By the way for smartphones one can install Esperanto support for the letters.

  • the point is using 'chashundo' instead of cx/sx etc; introduces kind of the same problem that Japanese has. The word 'し' (shi) can be 'four' (四) or 'death' (死). If it is typed in hiragana instead of kanji (as it would be for elementary school students) you can't tell the difference. That has actually resulted in a superstition in Japan where it's considered a bad omen to give somebody four of anything.
    – jastako
    Commented Sep 4, 2020 at 15:35

The x-system is a reform attempt to Esperanto. Yes, it also should be changed to the h-system, because the cases in which the x-system is used are often the same cases that the h-system can be used, such as in urls.

An example is in url paths:

(h-system) https://www.akademio-de-esperanto.org/serchilo.html vs (x-system) https://tubaro.aperu.net/?sp=v&ord=temp_ad&lingv=eo&kategori=cxio&pagx=2.

In the h-system, the breve is removed so the ´ŭ´ is stored as ´u´. The x-system reformists think this transformation would cause problems with ambiguity, which is why they formed it. However this thought is not true; ´ŭ´ and ´u´ are distinguishable by letter name: ŭo ≠ u.

For reference, here is the alphabet of Esperanto from the ekzercaro in the Fundamento de Esperanto:

Nomoj de la literoj: a, bo, co, ĉo, do, e, fo, go, ĝo, ho, ĥo, i, jo, ĵo, ko, lo, mo, no, o, po, ro, so, ŝo, to, u, ŭo, vo, zo.

So one can store each Esperanto letter by their name in the h-system, to fully capture and save Esperanto text by the h-system. For example: "aŭtismulo" would be stored in the h-system as [a uo to i so mo u lo o].

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