user-record: Add languages field

This field is like preferredLanguage, but takes a priority list of
languages instead. If an app isn't translated into a user's primary
language, it can fall back to one of the other languages in the list
thus making the app more accessible to the user.

For instance: in my experience, many Ukrainians are fluent in Russian,
often significantly better than English (especially if they are of a
generation that grew up during the USSR). Such a person might set this
new variable to ["uk_UA.UTF-8", "ru_UA.UTF-8"] so that software that
lacks Ukrainian translations will first try Russian translations before
defaulting to English.

Fixes #31290

1 files changed, 16 insertions, 5 deletions

diff --git a/docs/USER_RECORD.md b/docs/USER_RECORD.md
index 60f75bf39d..aba45c39f4 100644
--- a/docs/USER_RECORD.md
+++ b/docs/USER_RECORD.md
@@ -310,11 +310,22 @@ string. The string should be a `tzdata` compatible location string, for
 example: `Europe/Berlin`.
 
 `preferredLanguage` → A string indicating the preferred language/locale for the
-user. When logging in
+user. It is combined with the `additionalLanguages` field to initialize the `$LANG`
+and `$LANGUAGE` environment variables on login; see below for more details. This string
+should be in a format compatible with the `$LANG` environment variable, for example:
+`de_DE.UTF-8`.
+
+`additionalLanguages` → An array of strings indicating the preferred languages/locales
+that should be used in the event that translations for the `preferredLanguage` are
+missing, listed in order of descending priority. This allows multi-lingual users to
+specify all the languages that they know, so software lacking translations in the user's
+primary language can try another language that the user knows rather than falling back to
+the default English. All entries in this field must be valid locale names, compatible with
+the `$LANG` variable, for example: `de_DE.UTF-8`. When logging in
 [`pam_systemd`](https://www.freedesktop.org/software/systemd/man/pam_systemd.html)
-will automatically initialize the `$LANG` environment variable from this
-string. The string hence should be in a format compatible with this environment
-variable, for example: `de_DE.UTF8`.
+will prepend `preferredLanguage` (if set) to this list (if set), remove duplicates,
+and then automatically initialize the `$LANGUAGE` variable with the resulting list.
+It will also initialize `$LANG` variable with the first entry in the resulting list.
 
 `niceLevel` → An integer value in the range -20…19. When logging in
 [`pam_systemd`](https://www.freedesktop.org/software/systemd/man/pam_systemd.html)
@@ -744,7 +755,7 @@ that may be used in this section are identical to the equally named ones in the
 `regular` section (i.e. at the top-level object). Specifically, these are:
 
 `iconName`, `location`, `shell`, `umask`, `environment`, `timeZone`,
-`preferredLanguage`, `niceLevel`, `resourceLimits`, `locked`, `notBeforeUSec`,
+`preferredLanguage`, `additionalLanguages`, `niceLevel`, `resourceLimits`, `locked`, `notBeforeUSec`,
 `notAfterUSec`, `storage`, `diskSize`, `diskSizeRelative`, `skeletonDirectory`,
 `accessMode`, `tasksMax`, `memoryHigh`, `memoryMax`, `cpuWeight`, `ioWeight`,
 `mountNoDevices`, `mountNoSuid`, `mountNoExecute`, `cifsDomain`,