Although defining a unit in config.exs is enough to create, operate on and serialize an additional unit, it cannot be localised without defining localizations in an ex_cldr backend module. For example:

defmodule MyApp.Cldr do
  use Cldr.Unit.Additional

  use Cldr,
    locales: ["en", "fr", "de", "bs", "af", "af-NA", "se-SE"],
    default_locale: "en",
    providers: [Cldr.Number, Cldr.Unit, Cldr.List]

  unit_localization(:person, "en", :long,
    one: "{0} person",
    other: "{0} people",
    display_name: "people"
  )

  unit_localization(:person, "en", :short,
    one: "{0} per",
    other: "{0} pers",
    display_name: "people"
  )

  unit_localization(:person, "en", :narrow,
    one: "{0} p",
    other: "{0} p",
    display_name: "p"
  )
end

Note the additions to a typical ex_cldr backend module:

• use Cldr.Unit.Additional is required to define additional units

• use of the unit_localization/4 macro in order to define a localization.

One invocation of unit_localization should made for each combination of unit, locale and style.

Parameters to unit_localization/4

• unit is the name of the additional unit as an atom.

• locale is the locale name for this localization. It should be one of the locale configured in this backend although this cannot currently be confirmed at compile tiem.

• style is one of :long, :short, or :narrow.

• localizations is a keyword like of localization strings. Two keys - :display_name and :other are mandatory. They represent the localizations for a non-count display name and :other is the localization for a unit when no other pluralization is defined.

Localisations

Localization keyword list defines localizations that match the plural rules for a given locale. Plural rules for a given number in a given locale resolve to one of six keys:

• :zero
• :one (singular)
• :two (dual)
• :few (paucal)
• :many (also used for fractions if they have a separate class)
• :other (required—general plural form—also used if the language only has a single form)

Only the :other key is required. For english, providing keys for :one and :other is enough. Other languages have different grammatical requirements.

The key :display_name is used by the function Cldr.Unit.display_name/1 which is primarly used to support UI applications.