convert Unicode to lower/uppercase?

["Martin v. Löwis"]

jallan wrote:

> But that really doesn't work properly. According to Unicode specs and
> German usage the uppercase of "ß" is actually "SS", that is the single
> character "ß" should uppercase to two characters.

Can you cite exact chapter and verse of the Unicode specs that say so?
According to the Unicode database,

http://www.unicode.org/Public/UNIDATA/UnicodeData.txt

has neither an uppercase mapping, nor a lowercase mapping.

Also, in German, the uppercase mapping of ß is of ongoing debate.
For example, the Duden from 1919 says

| Für ß wird in großer Schrift SZ angewandt [...]. Die Verwendung
| _zweier_ Buchstaben für _einen_ Laut ist nur ein Notbehelf, der
| aufhören muß, sobald ein geeigneter Druckbuchstabe für das
| große ß geschaffen ist.

The usage of SZ has only been eliminated in the recent change of
the amtliche Rechtschreibung.

Regards,
Martin