There are several sun.text.resources.* and sun.util.resources.* locale data in rt.jar for Western locales, and other locale data are in lib/ext/localedata.jar. This was the historical artifact due to the fact that there were two distinct JREs available for Windows platforms (European/International). Now that there is only one Windows JRE, this Western/International division is irrelevant.

Now, there is a requirement from Profiles project on how to package locale data. For JDK8 without Jigsaw, it would be realistic to have US locale data (which is mandated by the spec, e.g., java.text.DateFormat.getAvailableLocales()) in rt.jar, and rest in localedata.jar, then on Java SE, they are mandatory while on Embedded they are optional.

With that, this enhancement intends to move those Western locale data in rt.jar into localedata.jar, except en_US locale data.