There are some unique CLDR features introduced in the version 27.0.0 since 21.0.1, i.e.,
- Parent locales support: "en" bundle in CLDR represents US English, where some English countries should not use. In CLDR 27, those locales falls back to World English (en-001), such as UK.
- "no inheritance marker" support. http://unicode.org/pipermail/cldr-users/2015-April/000286.html
- "alias" support.
- Generic calendar support: http://cldr.unicode.org/development/development-process/design-proposals/generic-calendar-data