Locale Requirements Template for Product Planning

A [locale](/glossary/customer-segmentation) combines a language with a region, defining not just which language to display but how to format dates, numbers, currencies, and addresses. French in France (fr-FR) uses comma decimals and European date format. French in Canada (fr-CA) uses different vocabulary and follows North American address conventions. Always specify locale (language + region), not just language.

The Unicode CLDR (Common Locale Data Repository) is the industry standard. It covers date/time formats, number formats, currency symbols, address formats, and measurement units for 600+ locales. ICU (International Components for Unicode) is the library that implements CLDR data in code. Most modern programming languages have CLDR-based formatting APIs (JavaScript's Intl, Java's java.text, Python's babel).

Detailed enough to write acceptance criteria. "Support Japanese" is not actionable. "Date displays as YYYY年M月D日, currency displays as 1,234 JPY (no decimals), address fields render in postal-code-first order" is testable and implementable. Include examples for every format.

Create one document per locale. Even locales that share a language (de-DE and de-AT) have differences in address format, tax rules, and cultural conventions. Grouping creates ambiguity. The overhead of maintaining separate docs is small compared to the cost of shipping the wrong format to a market. ---