# YMD Date (slash-separated)

Key: `datetime.date.ymd_slash`

Year/Month/Day with slash separators. Unambiguous due to year-first ordering. CLDR ja-JP short format; standard in Japanese and Taiwanese CSV exports.

Page: <https://meridian.online/docs/projects/finetype/types/datetime/date/ymd_slash>

Format: `%Y/%m/%d`

Samples: `2024/01/15`, `2023/12/31`, `2000/06/01`

## Written by

Each locale below writes this format with its CLDR date pattern at the styles named beside it.

`en` (ZA) short

## Background

### Origin

ISO 8601 uses the hyphen as the separator between the year, month and day of a date.[[1]](https://en.wikipedia.org/wiki/ISO_8601) The first edition of ISO 8601 was published as ISO 8601:1988 in June 1988.[[1]](https://en.wikipedia.org/wiki/ISO_8601) In ISO 8601, a solidus, /, is usually the designator that separates the two values of a time interval.[[1]](https://en.wikipedia.org/wiki/ISO_8601)

Wikipedia's article on Japanese date notation says the most commonly used date format in Japan is year, month, day, followed by the weekday.[[2]](https://en.wikipedia.org/wiki/Date_and_time_notation_in_Japan) Wikipedia's article on Japanese date notation shows the Gregorian all-numeric date in Japan written year/month/day with slashes.[[2]](https://en.wikipedia.org/wiki/Date_and_time_notation_in_Japan) Unicode's CLDR locale data gives y/MM/dd as both the short and the medium Gregorian date pattern for Japanese (ja).[[3]](https://raw.githubusercontent.com/unicode-org/cldr-json/main/cldr-json/cldr-dates-full/main/ja/ca-gregorian.json) CLDR gives y/MM/dd as the short Gregorian date pattern for South African English (en-ZA).[[4]](https://raw.githubusercontent.com/unicode-org/cldr-json/main/cldr-json/cldr-dates-full/main/en-ZA/ca-gregorian.json) Wikipedia's list of date formats by country gives yyyy/mm/dd as one of the English-language date formats in South Africa.[[5]](https://en.wikipedia.org/wiki/List_of_date_formats_by_country) Wikipedia's list of date formats by country gives yyyy/(m)m/(d)d and yyyy-mm-dd as short date formats in Taiwan.[[5]](https://en.wikipedia.org/wiki/List_of_date_formats_by_country) Wikipedia's list of date formats by country gives yyyy/mm/dd as the date format for Basque in Spain.[[5]](https://en.wikipedia.org/wiki/List_of_date_formats_by_country) Wikipedia's list of date formats by country gives yyyy/mm/dd as the short format in Iran for dates in the Persian calendar.[[5]](https://en.wikipedia.org/wiki/List_of_date_formats_by_country)

### Use

In CLDR's date pattern language, the length of the y field specifies the minimum number of digits for the year in most cases.[[6]](https://www.unicode.org/reports/tr35/tr35-dates.html) CLDR's short Gregorian date pattern for Traditional Chinese (zh-Hant) is y/M/d.[[7]](https://raw.githubusercontent.com/unicode-org/cldr-json/main/cldr-json/cldr-dates-full/main/zh-Hant/ca-gregorian.json) Wikipedia's list of date formats by country gives (yy)yy/(m)m/(d)d, with or without leading zeroes, among the casual date forms used in China.[[5]](https://en.wikipedia.org/wiki/List_of_date_formats_by_country) The Japanese Ministry of Health, Labour and Welfare's open-data CSV of newly confirmed COVID-19 cases writes its dates in the form 2020/1/16, without leading zeros.[[8]](https://covid19.mhlw.go.jp/public/opendata/newly_confirmed_cases_daily.csv)

Python's datetime documentation notes that, when used with strptime(), the leading zero is optional for %d and %m.[[9]](https://docs.python.org/3/library/datetime.html) If a column must hold strictly padded dates, check the text against a fixed ten-character pattern before casting, rather than relying on the parser to reject the short forms. (Meridian's view)

## Sources

1. [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) — secondary source
2. [Date and time notation in Japan](https://en.wikipedia.org/wiki/Date_and_time_notation_in_Japan) — secondary source
3. [cldr-json: cldr-dates-full/main/ja/ca-gregorian.json](https://raw.githubusercontent.com/unicode-org/cldr-json/main/cldr-json/cldr-dates-full/main/ja/ca-gregorian.json) — standard
4. [cldr-json: cldr-dates-full/main/en-ZA/ca-gregorian.json](https://raw.githubusercontent.com/unicode-org/cldr-json/main/cldr-json/cldr-dates-full/main/en-ZA/ca-gregorian.json) — standard
5. [List of date formats by country](https://en.wikipedia.org/wiki/List_of_date_formats_by_country) — secondary source
6. [Unicode Locale Data Markup Language (LDML) Part 4: Dates](https://www.unicode.org/reports/tr35/tr35-dates.html) — standard
7. [cldr-json: cldr-dates-full/main/zh-Hant/ca-gregorian.json](https://raw.githubusercontent.com/unicode-org/cldr-json/main/cldr-json/cldr-dates-full/main/zh-Hant/ca-gregorian.json) — standard
8. [newly\_confirmed\_cases\_daily.csv](https://covid19.mhlw.go.jp/public/opendata/newly_confirmed_cases_daily.csv) — dataset
9. [datetime — Basic date and time types](https://docs.python.org/3/library/datetime.html) — documentation