International date formats vary widely some using / , some using . and some using - as delimters -- the trick is to use one that has the same meaning world-wide.
The official ISO format is YYYY-MM-DD (like 2018-11-04) which is non-ambiguous (but not commonly used).
The real fun starts when using the / format for the date where the USA uses mm/dd/yyyy while pretty much everybody else uses the dd/mm/yyyy format so when dd<=12 AND mm<=12, the date is confusing to some part of the world.