Add ADR-0040

docs/decisions/0040-use-one-form-for-singular-and-plural.md

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+---
+nav_order: 40
+parent: Decision Records
+---
+<!-- we need to disable MD025, because we use the different heading "ADR Template" in the homepage (see above) than it is foreseen in the template -->
+<!-- markdownlint-disable-next-line MD025 -->
+# Use one language string for pluralization localization
+
+## Context and Problem Statement
+
+For user-facing messages, sometimes, it needs to be counted: E.g., 1 entry updated, 2 entries updated, etc.
+
+In some languages, there is not only "one" and "more than one", but other forms:
+
+* zero → “لم نزرع أي شجرة حتى الآن”
+* one → “لقد زرعنا شجرة ١ حتى الآن”
+* two → “لقد زرعنا شجرتين ٢ حتى الآن”
+* few → “لقد زرعنا ٣ شجرات حتى الآن”
+* many → “لقد زرعنا ١١ شجرة حتى الآن”
+* other → “لقد زرعنا ١٠٠ شجرة حتى الآن”
+
+(Example is from [Pluralization: A Guide to Localizing Plurals](https://phrase.com/blog/posts/pluralization/))
+
+How to localize pluralization?
+
+## Decision Drivers
+
+* Good English language
+* Good localization to other languages
+
+## Considered Options
+
+* Use one language string for pluralization (no explicit pluralization)
+* Use singular and plural
+* Handling of multiple forms
+
+## Decision Outcome
+
+Chosen option: "Use one form only (no explicit pluralization)", because it is the most easiest to handle in the code.
+
+## Pros and Cons of the Options
+
+### Use one language string for pluralization (no explicit pluralization)
+
+Example:
+
+- `Imported 0 entry(s)`
+- `Imported 1 entry(s)`
+- `Imported 12 entry(s)`
+
+The alternative form would by `entry(ies)`.
+
+* Good, because easy to handle in the code
+* Bad, because reads strange in English UI
+
+### Use singular and plural
+
+Example:
+
+- `Imported 0 entries`
+- `Imported 1 entry`
+- `Imported 12 entries`
+
+* Good, because reads well in English
+* Bad, because all localizations need to take an `if` check for the count
+* Bad, because Arabic not localized properly
+
+### Handling of multiple forms
+
+Example:
+
+- `Imported 0 entries`
+- `Imported 1 entry`
+- `Imported 12 entries`
+
+Code: `Localization.lang("Imported %0 entries", "Imported %0 entry.", "Imported %0 entries.", "Imported %0 entries.", "Imported %0 entries.", "Imported %0 entries.", count)`
+
+* Good, because reads well in English
+* Bad, because sophisticated localization handling is required
+* Bad, because no Java library for handling pluralization is known
+* Bad, because Arabic not localized properly
+
+## More Information
+
+- [Language Plural Rules](https://www.unicode.org/cldr/charts/43/supplemental/language_plural_rules.html)
+- [Unicode CLDR Project's Plural Rules](https://cldr.unicode.org/index/cldr-spec/plural-rules)
+- [Implementation in Mozilla Firefox](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/PluralRules)
+- [SX discussion on plural forms](https://english.stackexchange.com/a/90283/66058)
+
+<!-- markdownlint-disable-file MD004 -->