Roman Numerals for Months Avoid Ambiguity.

In most countries of the world the day-month-year date format is used. On various official forms it is represented as DD/MM/YY for double digit representation.

The US tradition of putting the month before the day sometimes is confusing, even to professionals. One translator cited an example of a colleague mistakenly translating 9/11 as the ninth of November!

I was teaching English students about days, dates, months and years in Russian and mentioned in passing that Roman numerals are traditionally used to represent months, i.e. American 9/11 (September the eleventh) would be IX/11 with Roman numerals for months, while in Russian/European format it would be 11/IX (the eleventh of September). Some were quite impressed (the group of adult professionals included Brits, Americans, Italians and Chinese) with how easy it makes to avoid confusion between American and non-American dates.

Arabic numerals are commonly used these days for months alongside Roman. When pronounced the month can also be referred to by its number, одиннадцатого девятого. Even though 9/11 is recognised in Russia for what it represents, the awkwardness of quickly switching from one format to the other is still preventing 9/11 from being widely used. Instead the phrase "attack on the Twin Towers" — "атака на Башни-близнецы" is used.

A map of date formats used in the world (graphic by Typhoon2013). Cyan for DD/MM, magenta for MM/DD —