I've recently discovered that `ToUpperCase` is quite unreliable on non-ASCII input:

![see code below][1]

 In[31]:= ToUpperCase@{"éàÇœßþσς", "ijķnjđӽծ", "ÿ"}
 Out[31]= {"ÉÀÇŒSSÞ∑∑", "ijķnjđӽծ", "Y"}

So: it handles some accented ASCII, ligatures, Western European stuff, greek and cyrillic, while it fails on others (returning the lowercase characters themselves when they have valid uppercase variants). In at least one case, it fails utterly ([the uppercase version of `ÿ` is `Ÿ`][2], not `Y`).

Mathematica’s documentation is very short on specifics on Unicode support. It [broadly states][3] that:

> Mathematica has efficient systemwide 16-bit Unicode support, allowing a full range of international, technical and other character sets and character encodings.

which of course I very much doubt after seeing the above. More specifically, the [`ToUpperCase` doc][4] does not include a mention of Unicode. I even uses my example of a buggy transform (`ÿ`) to warn you that “for a few characters, ToLowerCase is not the inverse of ToUpperCase:”

![enter image description here][5]



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So, after that bleak assessment, the question is the following: **how do I get better Unicode-compliant string manipulation functions?** (mostly `ToUpperCase` and `ToLowerCase` for now, but I'm sure others will be a problem for me in the future). Are there internal functions that do this, or external packages? Have I missed something in M’s documentation?


 [1]: https://i.sstatic.net/my6SR.png
 [2]: http://www.fileformat.info/info/unicode/char/ff/index.htm
 [3]: http://reference.wolfram.com/mathematica/guide/CharacterOperations.html
 [4]: http://reference.wolfram.com/mathematica/ref/ToUpperCase.html
 [5]: https://i.sstatic.net/NvSl2.png