Token Mapping

This is the grammar layer — what translates between dialects, independent of any tool. Each row is one canonical meaning and the token each dialect uses to spell it. Behaviour specific to a concrete library lives in Library Notes.

The tables below list the tokens that round-trip between dialects.

Era & year

Meaning	`moment`	`ldml`
Era, abbreviated	`N`	`GGG`
Era, wide	`NNNN`	`GGGG`
Era, narrow	`NNNNN`	`GGGGG`
Calendar year	`YYYY`	`yyyy`
Calendar year, 2-digit	`YY`	`yy`
Local week-numbering year	`gggg`	`YYYY`
Local week-numbering year, 2-digit	`gg`	`YY`

Month & quarter

Meaning	`moment`	`ldml`
Quarter	`Q`	`Q`
Quarter, ordinal	`Qo`	`Qo`
Month	`M`	`M`
Month, 2-digit	`MM`	`MM`
Month, ordinal	`Mo`	`Mo`
Month, abbreviated	`MMM`	`MMM`
Month, wide	`MMMM`	`MMMM`

Week & day

Meaning	`moment`	`ldml`
Week of year	`w`	`w`
Week of year, 2-digit	`ww`	`ww`
Week of year, ordinal	`wo`	`wo`
Day of month	`D`	`d`
Day of month, 2-digit	`DD`	`dd`
Day of month, ordinal	`Do`	`do`
Day of year	`DDD`	`D`
Day of year, 3-digit	`DDDD`	`DDD`
Day of year, ordinal	`DDDo`	`Do`

Weekday

Meaning	`moment`	`ldml`
Weekday, abbreviated	`ddd`	`EEE`
Weekday, wide	`dddd`	`EEEE`
Weekday, short	`dd`	`EEEEEE`
Weekday, number	`d`	`e`

Time

Meaning	`moment`	`ldml`
AM/PM	`A`	`a`
Hour 1–12	`h`	`h`
Hour 1–12, 2-digit	`hh`	`hh`
Hour 0–23	`H`	`H`
Hour 0–23, 2-digit	`HH`	`HH`
Hour 1–24	`k`	`k`
Hour 1–24, 2-digit	`kk`	`kk`
Minute	`m`	`m`
Minute, 2-digit	`mm`	`mm`
Second	`s`	`s`
Second, 2-digit	`ss`	`ss`
Fractional second (1–3 digits)	`S` `SS` `SSS`	`S` `SS` `SSS`

Time zone

Meaning	`moment`	`ldml`
Time-zone name	`z`	`zzz`
Offset, `±hh:mm`	`Z`	`xxx`
Offset, `±hhmm`	`ZZ`	`xx`

Aliases

A few extra spellings are parsed but normalize to the primary token above when rendered:

moment Y → calendar year (like YYYY).
ldml y / yyy → calendar year; EE → abbreviated weekday; aa / aaa → AM/PM; z / zz → time-zone name.

Tokens with no `moment` counterpart

Some ldml tokens have no moment counterpart, so converting them to moment produces an escaped literal (e.g. MMMMM → [MMMMM]) rather than a wrong guess.

`ldml`	Meaning
`MMMMM`	Narrow month
`EEEEE`	Narrow weekday
`aaaa` `aaaaa`	Wide / narrow day period
`K` `KK`	Hour 0–11
`DD`	Day of year, 2-digit

A few mappings are intentionally lossy. moment d (weekday number, 0–6) and ldml e (locale-dependent) map to each other but use different numbering; the AM/PM marker loses its moment casing (A/a both become a); and moment’s narrow era (NNNNN) renders the abbreviation (AD), not a true one-character form.

date-fns adds extension tokens that also have no moment counterpart (PPPP, Pp, …). Localized preset behaviour is covered in Library Notes → Localized presets.