CLDR EEE

Weekday, abbreviated.

Mon

at the reference instant, Mon, Jan 2 2006, 3:04:05 PM MST

The short weekday name (Mon). CLDR uses E–EEE for the abbreviation; strftime %a. Locale-dependent except in Go.

Language	Token	Caveat
C / POSIX strftime	%a
C# custom format	ddd
CLDR / ICU pattern	E	E, EE and EEE are all the abbreviation; EEEEE is narrow, EEEEEE short. e and c add locale-dependent numeric forms.
Go time layout	Mon
Java DateTimeFormatter	EEE	E and EE are the same short form; e gives the localized weekday number instead.
JavaScript Intl.DateTimeFormat	weekday: "short"	weekday: "narrow" gives a single letter (T).
Moment.js format	ddd
PHP date()	D
Python strftime	%a
Ruby strftime	%a
Rust chrono	%a	Always three letters.