Last updated at 9:04 am UTC on 15 December 2015
ICU is a mature, widely used set of C/C++ and Java libraries providing Unicode and Globalization support for software applications. ICU is widely portable and gives applications the same results on all platforms and between C/C++ and Java software.
ICU uses UTF-16 internally (Source). This does not fit well with the 32bit used by the Squeak class Character.
Unicode in Squeak