What is the purpose of “[Developer] Accented English" (zz-ZZ) on Android?
In Android KitKat, if I select "Settings"> "Language" and "Enter"> "Language", the first I offer [Developer] Accented English. This replaces every Roman letter with an accented version. You can find a list of all character mappings here . (It helps if you can read French).
What is the purpose of this parameter? Is it just to show how characters can be matched with other characters? Or can it be used productively (for example, to create specific phonemes in text to speech?
This is a method called 'Pseudolocalization' and it has been used to help verify that the application handles localization aspects correctly.
The idea is that instead of expecting application string resources to be translated into other languages, which may take some time, a pseudo-sheet alias is used instead. If an application behaves well against this fake translation, then most likely it will work well with actual translations. There are various options for pseudolocation, but most of them usually do some of the following:
Add parens [...] or other delimiters around the line: this makes it easier to ensure that lines are not trimmed at either end.
Replace regular characters with accented characters: if you see a string without accented characters, it means that it can be hard-coded and not treated as a localized resource. (Previously, it was also used to ensure that applications can correctly process non-ASCII characters and not lose data in codepage translation, although this is now a problem when modern platforms support Unicode.)
Add string addition: this is for modeling languages such as German, which often have longer translations for the corresponding English string. If the filled string is truncated instead of wrapping or flowing, then probably the German string will do the same.
Add famous characters as “canaries”: on some platforms, characters from certain parts of the Unicode range can be added to ensure that they are handled or supported properly. For example, Chinese Chinese can be added to provide support for Chinese fonts: if it appears as an empty square, this may indicate a problem. Other common "canary" characters include code points outside the BMP or using character combining .
One of the advantages of using pseudo-localization over the actual translation is that testing can be performed by someone who does not understand the target language: “[Àççôûñţ Šéţţîñĝš ___]” is still visually similar to the source text in English “Account Settings”. If you try to use it with a Screen-Reader such as TalkBack, or in another wise way to send pseudo-localized text to text to speech, you will probably get nonsense, as it will try to treat accented characters as actual accented characters.