CLDR MMM

Month name, abbreviated.

Jan

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

The short month name (Jan). Locale-dependent everywhere: strftime %b follows the process locale, CLDR MMM follows the formatter's locale, Go always prints English.

LanguageTokenCaveat
C / POSIX strftime%b%h is defined as an exact equivalent.
C# custom formatMMMCulture-sensitive: Jun in en-US, juin in fr-FR.
CLDR / ICU patternMMMMMMMM gives the narrow single-letter form; LLL is the stand-alone variant.
Go time layoutJan
Java DateTimeFormatterMMML instead of M gives the stand-alone form some languages need outside a full date.
JavaScript Intl.DateTimeFormatmonth: "short"month: "narrow" gives a single letter (M).
Moment.js formatMMM
PHP date()M
Python strftime%b
Ruby strftime%b%h is a documented synonym.
Rust chrono%bAlways three letters; %h is a synonym.

Definition anchored to Unicode UTS #35 — Date Field Symbol Table.