Prefix

Quoting from Prefix Project: "To bring out the virtues of Gentoo Linux on different operating systems, the Gentoo Prefix project develops and maintains a way of installing Gentoo systems in a non-standard location, designated by a 'prefix'."

Prefix libc
Libc inside prefix is now possible to bootstrap on many different linux boxes.

Use Cases
Setup CJK in Prefix on hosts without such support.