# @northguild/gmt

> Temporal-first date and time utilities with timezone support and polyfill integration.

## Reference — duration

- [absDuration](https://gmt-dox.northguild.workers.dev/reference/duration/calculate/absDuration.md): Return the absolute value of an ISO 8601 duration string.
- [addDuration](https://gmt-dox.northguild.workers.dev/reference/duration/calculate/addDuration.md): Combine two ISO 8601 duration strings by addition.
- [compareDurations](https://gmt-dox.northguild.workers.dev/reference/duration/compare/compareDurations.md): Compare two ISO 8601 duration strings by length.
- [durationAs](https://gmt-dox.northguild.workers.dev/reference/duration/calculate/durationAs.md): Express an ISO 8601 duration as a single fractional total in one unit.
- [DurationUnit](https://gmt-dox.northguild.workers.dev/reference/duration/format/DurationUnit.md): The DurationUnit type.
- [formatDuration](https://gmt-dox.northguild.workers.dev/reference/duration/format/formatDuration.md): Render an ISO 8601 duration string as a locale-aware, human-readable string.
- [FormatDurationOptions](https://gmt-dox.northguild.workers.dev/reference/duration/format/FormatDurationOptions.md): The FormatDurationOptions type.
- [getDurationSign](https://gmt-dox.northguild.workers.dev/reference/duration/calculate/getDurationSign.md): Report whether an ISO 8601 duration is negative, zero-length, or positive.
- [getDurationUnit](https://gmt-dox.northguild.workers.dev/reference/duration/calculate/getDurationUnit.md): Read a single component out of an ISO 8601 duration string.
- [isValidDuration](https://gmt-dox.northguild.workers.dev/reference/duration/validate/isValidDuration.md): Return true if `value` is a valid ISO 8601 duration string.
- [negateDuration](https://gmt-dox.northguild.workers.dev/reference/duration/calculate/negateDuration.md): Flip the sign of an ISO 8601 duration string.
- [normalizeDuration](https://gmt-dox.northguild.workers.dev/reference/duration/normalize/normalizeDuration.md): Roll an ISO 8601 duration string's small units into larger ones.
- [parseDuration](https://gmt-dox.northguild.workers.dev/reference/duration/parse/parseDuration.md): Parse and re-normalize an ISO 8601 duration string.
- [subtractDuration](https://gmt-dox.northguild.workers.dev/reference/duration/calculate/subtractDuration.md): Combine two ISO 8601 duration strings by subtraction.

## Reference — plain

- [addBusinessDays](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/addBusinessDays.md): Return a PlainDate ISO string with `amount` business days added to `value`.
- [addDate](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/addDate.md): Return a PlainDate ISO string with `amount` added according to `units`.
- [addDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/addDateTime.md): Return a PlainDateTime ISO string with `units` added to `value`.
- [addTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/addTime.md): Return a PlainTime ISO string with `units` added to `value`.
- [areDatesEqual](https://gmt-dox.northguild.workers.dev/reference/plain/compare/areDatesEqual.md): Compare two ISO date-like strings for equality, ignoring time components.
- [areDatesEqualBy](https://gmt-dox.northguild.workers.dev/reference/plain/compare/areDatesEqualBy.md): Compare two ISO date strings for equality at a given calendar unit.
- [areDateTimesEqual](https://gmt-dox.northguild.workers.dev/reference/plain/compare/areDateTimesEqual.md): Return true if two PlainDateTime ISO strings represent the same instant of local date/time components.
- [areDateTimesEqualBy](https://gmt-dox.northguild.workers.dev/reference/plain/compare/areDateTimesEqualBy.md): Compare two ISO datetime strings for equality at a given unit.
- [areTimesEqual](https://gmt-dox.northguild.workers.dev/reference/plain/compare/areTimesEqual.md): Return true if two PlainTime ISO strings represent the same time components.
- [chopDate](https://gmt-dox.northguild.workers.dev/reference/plain/chop/chopDate.md): Return the PlainTime portion extracted from an ISO PlainDateTime string.
- [chopMilliseconds](https://gmt-dox.northguild.workers.dev/reference/plain/chop/chopMilliseconds.md): Return a string with millisecond precision removed from a PlainDateTime or PlainTime value.
- [chopSeconds](https://gmt-dox.northguild.workers.dev/reference/plain/chop/chopSeconds.md): Return an ISO string with second precision removed from a PlainDateTime or PlainTime value.
- [chopTime](https://gmt-dox.northguild.workers.dev/reference/plain/chop/chopTime.md): Return the PlainDate portion extracted from an ISO PlainDateTime string.
- [clampDate](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/clampDate.md): Restrict `value` to the range [`min`, `max`].
- [closestDateTo](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/closestDateTo.md): Return the candidate date nearest to `target` by calendar distance.
- [convertDateToCalendar](https://gmt-dox.northguild.workers.dev/reference/plain/convert/convertDateToCalendar.md): Convert a PlainDate to the same date expressed in a different calendar system.
- [cycleDate](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/cycleDate.md): Return a PlainDate ISO string with `field` cycled by `amount`, wrapping at that field's own
- [cycleDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/cycleDateTime.md): Return a PlainDateTime ISO string with `field` cycled by `amount`, wrapping at that field's own
- [cycleTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/cycleTime.md): Return a PlainTime ISO string with `field` cycled by `amount`, wrapping at that field's own
- [diffDate](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/diffDate.md): Return the difference between two PlainDate values using the provided `unit`.
- [diffDateAsDuration](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/diffDateAsDuration.md): Return the difference between two PlainDate values as an ISO 8601 duration string,
- [diffDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/diffDateTime.md): Return the difference between two PlainDateTime values in the requested unit.
- [diffDateTimeAsDuration](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/diffDateTimeAsDuration.md): Return the difference between two PlainDateTime values as an ISO 8601 duration string,
- [diffTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/diffTime.md): Return the difference between two PlainTime values in the requested unit.
- [endOfDate](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/endOfDate.md): Return the end of the specified date `unit` for a given ISO 8601 date string.
- [endOfDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/endOfDateTime.md): Return the end of the specified date-time `unit` for a given ISO 8601 datetime string.
- [endOfQuarterForDate](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/endOfQuarterForDate.md): Return the last day of the quarter for a given ISO date.
- [endOfQuarterForDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/endOfQuarterForDateTime.md): Return the end of the quarter for a given ISO datetime.
- [endOfTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/endOfTime.md): Return the end of the specified time `unit` for a given ISO 8601 time string.
- [EndOfTimeUnit](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/EndOfTimeUnit.md): The EndOfTimeUnit type.
- [formatCalendar](https://gmt-dox.northguild.workers.dev/reference/plain/format/formatCalendar.md): Format a plain date-time as a relative day label plus time-of-day, e.g.
- [FormatCalendarOptions](https://gmt-dox.northguild.workers.dev/reference/plain/format/FormatCalendarOptions.md): The FormatCalendarOptions type.
- [formatDate](https://gmt-dox.northguild.workers.dev/reference/plain/format/formatDate.md): Return a localized string for a PlainDate ISO input using Intl options.
- [formatDateRange](https://gmt-dox.northguild.workers.dev/reference/plain/format/formatDateRange.md): Format a plain date range using the Temporal Intl.DateTimeFormat formatRange API.
- [formatDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/format/formatDateTime.md): Return a localized string for a PlainDateTime ISO input using Intl options.
- [formatDateTimeRange](https://gmt-dox.northguild.workers.dev/reference/plain/format/formatDateTimeRange.md): Format a plain datetime range using the Temporal Intl.DateTimeFormat formatRange API.
- [formatDateTimeToParts](https://gmt-dox.northguild.workers.dev/reference/plain/format/formatDateTimeToParts.md): Return the locale-formatted parts of a PlainDateTime.
- [formatDateToParts](https://gmt-dox.northguild.workers.dev/reference/plain/format/formatDateToParts.md): Return the locale-formatted parts of a PlainDate.
- [formatRelativeDate](https://gmt-dox.northguild.workers.dev/reference/plain/format/formatRelativeDate.md): Format the relative time between a plain date and a reference date.
- [FormatRelativeDateOptions](https://gmt-dox.northguild.workers.dev/reference/plain/format/FormatRelativeDateOptions.md): The FormatRelativeDateOptions type.
- [formatRelativeDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/format/formatRelativeDateTime.md): Format the relative time between a plain date-time and a reference date-time.
- [FormatRelativeDateTimeOptions](https://gmt-dox.northguild.workers.dev/reference/plain/format/FormatRelativeDateTimeOptions.md): The FormatRelativeDateTimeOptions type.
- [formatRelativeTime](https://gmt-dox.northguild.workers.dev/reference/plain/format/formatRelativeTime.md): Format the relative time between a plain time and a reference time.
- [FormatRelativeTimeOptions](https://gmt-dox.northguild.workers.dev/reference/plain/format/FormatRelativeTimeOptions.md): The FormatRelativeTimeOptions type.
- [formatSql](https://gmt-dox.northguild.workers.dev/reference/plain/format/formatSql.md): Format a plain ISO 8601 datetime string as an ANSI SQL / ODBC datetime
- [formatTime](https://gmt-dox.northguild.workers.dev/reference/plain/format/formatTime.md): Return a localized string for a PlainTime ISO input using Intl options.
- [getDay](https://gmt-dox.northguild.workers.dev/reference/plain/get/getDay.md): Return the current day of month using the system timeZone.
- [getDayOfWeek](https://gmt-dox.northguild.workers.dev/reference/plain/get/getDayOfWeek.md): Return the current ISO day of the week as a number in the system timeZone.
- [getDayOfYear](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/getDayOfYear.md): Return the ordinal day-of-year (1-based) for `value`.
- [getDaysInMonth](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/getDaysInMonth.md): Return the number of days in the month containing `value`.
- [getDaysInYear](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/getDaysInYear.md): Return the number of days in the calendar year containing `value`.
- [getHour](https://gmt-dox.northguild.workers.dev/reference/plain/get/getHour.md): Return the current hour using the system timeZone.
- [getLargestDateDurationUnit](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/getLargestDateDurationUnit.md): Return the largest DateDurationUnit from the provided array.
- [getLargestDateTimeDurationUnit](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/getLargestDateTimeDurationUnit.md): Return the largest DateTimeDurationUnit from the provided array.
- [getLargestTimeDurationUnit](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/getLargestTimeDurationUnit.md): Return the largest TimeDurationUnit from the provided array.
- [getLocaleDayOfWeek](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/getLocaleDayOfWeek.md): Return the locale-relative day-of-week index for `value`.
- [getLocaleEndOfWeek](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/getLocaleEndOfWeek.md): Return the end of the week containing `value`, using `locale`'s first
- [getLocaleEraNames](https://gmt-dox.northguild.workers.dev/reference/plain/locale/getLocaleEraNames.md): Return a locale's Gregorian era names as [BCE-label, CE-label].
- [getLocaleMeridiems](https://gmt-dox.northguild.workers.dev/reference/plain/locale/getLocaleMeridiems.md): Return a locale's AM/PM (day-period) labels as `[AM-label, PM-label]`.
- [getLocaleMonthNames](https://gmt-dox.northguild.workers.dev/reference/plain/locale/getLocaleMonthNames.md): Return the 12 Gregorian calendar-month names for a locale, in calendar
- [getLocaleStartOfWeek](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/getLocaleStartOfWeek.md): Return the start of the week containing `value`, using `locale`'s
- [getLocaleWeekdayNames](https://gmt-dox.northguild.workers.dev/reference/plain/locale/getLocaleWeekdayNames.md): Return the 7 weekday names for a locale, ordered starting from the
- [getLocaleWeekYear](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/getLocaleWeekYear.md): Return the locale-relative week-numbering year `value` belongs to,
- [getMicrosecond](https://gmt-dox.northguild.workers.dev/reference/plain/get/getMicrosecond.md): Return the current microsecond using the system timeZone.
- [getMillisecond](https://gmt-dox.northguild.workers.dev/reference/plain/get/getMillisecond.md): Return the current millisecond using the system timeZone.
- [getMinute](https://gmt-dox.northguild.workers.dev/reference/plain/get/getMinute.md): Return the current minute using the system timeZone.
- [getMonth](https://gmt-dox.northguild.workers.dev/reference/plain/get/getMonth.md): Return the current month using the system timeZone.
- [getNanosecond](https://gmt-dox.northguild.workers.dev/reference/plain/get/getNanosecond.md): Return the current nanosecond using the system timeZone.
- [getNow](https://gmt-dox.northguild.workers.dev/reference/plain/get/getNow.md): Return the current local PlainDateTime as an ISO string using the system timeZone.
- [getNowUnit](https://gmt-dox.northguild.workers.dev/reference/plain/get/getNowUnit.md): Return the requested current unit value using the system timeZone.
- [getQuarterForDate](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/getQuarterForDate.md): Return the quarter of the year (1-4) for a given ISO date.
- [getQuarterForDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/getQuarterForDateTime.md): Return the quarter of the year (1-4) for a given ISO datetime.
- [getSecond](https://gmt-dox.northguild.workers.dev/reference/plain/get/getSecond.md): Return the current second using the system timeZone.
- [getToday](https://gmt-dox.northguild.workers.dev/reference/plain/get/getToday.md): Return the current PlainDate as an ISO string in the system timeZone.
- [getWeekNumber](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/getWeekNumber.md): Calculate the week number based on configurable week start day.
- [getWeekOfMonth](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/getWeekOfMonth.md): Return the 1-based row `value` falls on within its month's calendar
- [getWeekOfYear](https://gmt-dox.northguild.workers.dev/reference/plain/get/getWeekOfYear.md): Get the ISO week number of the current date.
- [getWeeksInLocaleWeekYear](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/getWeeksInLocaleWeekYear.md): Return the number of weeks (52 or 53) in the locale week-numbering year
- [getWeeksInMonth](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/getWeeksInMonth.md): Return the number of calendar-grid rows (4, 5, or 6) `value`'s month
- [getWeeksInYear](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/getWeeksInYear.md): Return the number of ISO weeks (52 or 53) in the ISO week-numbering year
- [getWeekYear](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/getWeekYear.md): Return the ISO 8601 week-numbering year `value` belongs to.
- [getYear](https://gmt-dox.northguild.workers.dev/reference/plain/get/getYear.md): Return the current year as a zero-padded string in the system timeZone.
- [intervalAbutsDate](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalAbutsDate.md): Return true when two date intervals are exactly adjacent — one's end equals the other's start
- [intervalAbutsDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalAbutsDateTime.md): Return true when two datetime intervals are exactly adjacent — one's end equals the other's
- [intervalAbutsTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalAbutsTime.md): Return true when two time intervals are exactly adjacent — one's end equals the other's start
- [intervalContainsDate](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalContainsDate.md): Return true when `pointOrStart` falls within the interval `[intervalStart, intervalEnd]`
- [intervalContainsDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalContainsDateTime.md): Return true when `pointOrStart` falls within the interval `[intervalStart, intervalEnd]`
- [intervalContainsTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalContainsTime.md): Return true when `pointOrStart` falls within the interval `[intervalStart, intervalEnd]`
- [intervalCountDate](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalCountDate.md): Count how many `unit` boundaries a date interval crosses.
- [intervalCountDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalCountDateTime.md): Count how many `unit` boundaries a date-time interval crosses.
- [intervalCountTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalCountTime.md): Count how many `unit` boundaries a time interval crosses.
- [intervalDifferenceDate](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalDifferenceDate.md): Return the portion(s) of interval A not covered by interval B.
- [intervalDifferenceDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalDifferenceDateTime.md): Return the portion(s) of interval A not covered by interval B.
- [intervalDifferenceTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalDifferenceTime.md): Return the portion(s) of interval A not covered by interval B.
- [intervalDivideEquallyDate](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalDivideEquallyDate.md): Split a date interval into `n` equal-length sub-intervals.
- [intervalDivideEquallyDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalDivideEquallyDateTime.md): Split a datetime interval into `n` equal-length sub-intervals.
- [intervalDivideEquallyTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalDivideEquallyTime.md): Split a time interval into `n` equal-length sub-intervals.
- [intervalEngulfsDate](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalEngulfsDate.md): Return true when interval B is fully contained within interval A — every instant of B
- [intervalEngulfsDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalEngulfsDateTime.md): Return true when interval B is fully contained within interval A — every instant of B
- [intervalEngulfsTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalEngulfsTime.md): Return true when interval B is fully contained within interval A — every instant of B
- [intervalFromDurationDate](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalFromDurationDate.md): Construct a date interval from a single point plus an ISO 8601 duration, anchored at either end.
- [intervalFromDurationDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalFromDurationDateTime.md): Construct a datetime interval from a single point plus an ISO 8601 duration, anchored at either end.
- [intervalFromDurationTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalFromDurationTime.md): Construct a time interval from a single point plus an ISO 8601 duration, anchored at either end.
- [intervalIntersectionDate](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalIntersectionDate.md): Return the overlapping span of two date intervals, or null when they do not overlap.
- [intervalIntersectionDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalIntersectionDateTime.md): Return the overlapping span of two datetime intervals, or null when they do not overlap.
- [intervalIntersectionTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalIntersectionTime.md): Return the overlapping span of two time intervals, or null when they do not overlap.
- [intervalLengthDate](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalLengthDate.md): Return the exact length of a date interval in `unit`, as a real (possibly fractional) number.
- [intervalLengthDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalLengthDateTime.md): Return the exact length of a datetime interval in `unit`, as a real (possibly fractional) number.
- [intervalLengthTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalLengthTime.md): Return the exact length of a time interval in `unit`, as a real (possibly fractional) number.
- [intervalOverlappingDaysDate](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalOverlappingDaysDate.md): Return how many distinct calendar dates two date intervals share.
- [intervalOverlappingDaysDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalOverlappingDaysDateTime.md): Return how many distinct calendar dates two datetime intervals share.
- [intervalsOverlapDate](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalsOverlapDate.md): Return true when intervals `[aStart, aEnd]` and `[bStart, bEnd]` share at least one instant.
- [intervalsOverlapDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalsOverlapDateTime.md): Return true when intervals `[aStart, aEnd]` and `[bStart, bEnd]` share at least one instant.
- [intervalsOverlapTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalsOverlapTime.md): Return true when intervals `[aStart, aEnd]` and `[bStart, bEnd]` share at least one instant.
- [intervalSplitAtDate](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalSplitAtDate.md): Split a date interval at arbitrary `points`, producing consecutive sub-intervals.
- [intervalSplitAtDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalSplitAtDateTime.md): Split a datetime interval at arbitrary `points`, producing consecutive sub-intervals.
- [intervalSplitAtTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalSplitAtTime.md): Split a time interval at arbitrary `points`, producing consecutive sub-intervals.
- [intervalUnionDate](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalUnionDate.md): Return the combined span of two date intervals, or null when they are disjoint.
- [intervalUnionDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalUnionDateTime.md): Return the combined span of two datetime intervals, or null when they are disjoint.
- [intervalUnionTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalUnionTime.md): Return the combined span of two time intervals, or null when they are disjoint.
- [intervalXorAllDate](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalXorAllDate.md): Return the symmetric difference across a list of date intervals — the set of dates covered
- [intervalXorAllDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalXorAllDateTime.md): Return the symmetric difference across a list of datetime intervals — the set of instants
- [intervalXorAllTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalXorAllTime.md): Return the symmetric difference across a list of time intervals — the set of clock times
- [intervalXorDate](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalXorDate.md): Return the symmetric difference of two date intervals — time covered by exactly one interval.
- [intervalXorDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalXorDateTime.md): Return the symmetric difference of two datetime intervals — time covered by exactly one interval.
- [intervalXorTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/intervalXorTime.md): Return the symmetric difference of two time intervals — time covered by exactly one interval.
- [isAfterDate](https://gmt-dox.northguild.workers.dev/reference/plain/compare/isAfterDate.md): Return true if the first ISO PlainDate string represents a date after the second.
- [isAfterDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/compare/isAfterDateTime.md): Return true when `value1` is strictly after `value2` for PlainDateTime values.
- [isAfterTime](https://gmt-dox.northguild.workers.dev/reference/plain/compare/isAfterTime.md): Return true when `value1` is strictly after `value2` for PlainTime values.
- [isBeforeDate](https://gmt-dox.northguild.workers.dev/reference/plain/compare/isBeforeDate.md): Return true when `value1` is strictly before `value2` for PlainDate values.
- [isBeforeDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/compare/isBeforeDateTime.md): Return true when `value1` is strictly before `value2` for PlainDateTime values.
- [isBeforeTime](https://gmt-dox.northguild.workers.dev/reference/plain/compare/isBeforeTime.md): Return true when `value1` is strictly before `value2` for PlainTime values.
- [isBetweenDate](https://gmt-dox.northguild.workers.dev/reference/plain/compare/isBetweenDate.md): Return true when `date` is between `start` and `end` (inclusive by default).
- [isBetweenDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/compare/isBetweenDateTime.md): Return true when `dateTime` is between `start` and `end` (inclusive by default).
- [isBetweenTime](https://gmt-dox.northguild.workers.dev/reference/plain/compare/isBetweenTime.md): Return true when `time` is between `start` and `end` (inclusive by default).
- [isBusinessDay](https://gmt-dox.northguild.workers.dev/reference/plain/compare/isBusinessDay.md): Return true when `value` falls on a Monday–Friday ISO business day.
- [isFuture](https://gmt-dox.northguild.workers.dev/reference/plain/compare/isFuture.md): Return true when `value` is strictly after today, per the system clock
- [isLeapSecond](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isLeapSecond.md): Return true if the provided string is a valid ISO 8601 leap second datetime.
- [isLeapYear](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isLeapYear.md): Return true when the given PlainDate falls in a leap year.
- [isPast](https://gmt-dox.northguild.workers.dev/reference/plain/compare/isPast.md): Return true when `value` is strictly before today, per the system clock
- [isRelativeDay](https://gmt-dox.northguild.workers.dev/reference/plain/compare/isRelativeDay.md): Return true when `value` falls `offsetDays` days from today, per the
- [isThisUnit](https://gmt-dox.northguild.workers.dev/reference/plain/compare/isThisUnit.md): Return true when `value` falls in the same `unit` as today, per the
- [isValidCalendarDate](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isValidCalendarDate.md): Return true if `value` is a valid GMT PlainDate string: a plain ISO date
- [isValidDate](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isValidDate.md): Return true if `value` is a valid ISO PlainDate string.
- [isValidDateCycleField](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isValidDateCycleField.md): Return true when `field` is a valid DateCycleField.
- [isValidDateDurationUnit](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isValidDateDurationUnit.md)
- [isValidDateInterval](https://gmt-dox.northguild.workers.dev/reference/plain/interval/isValidDateInterval.md): Return true if `start` and `end` form a valid date interval — both parseable as
- [isValidDateRange](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isValidDateRange.md): Return whether `value1` is before `value2`.
- [IsValidDateRangeProps](https://gmt-dox.northguild.workers.dev/reference/plain/validate/IsValidDateRangeProps.md): The IsValidDateRangeProps type.
- [isValidDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isValidDateTime.md): Return true when `value` is a valid PlainDateTime string.
- [isValidDateTimeCycleField](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isValidDateTimeCycleField.md): Return true when `field` is a valid DateTimeCycleField (a valid DateCycleField or
- [isValidDateTimeDurationUnit](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isValidDateTimeDurationUnit.md)
- [isValidDateTimeInterval](https://gmt-dox.northguild.workers.dev/reference/plain/interval/isValidDateTimeInterval.md): Return true if `start` and `end` form a valid datetime interval — both parseable as
- [isValidDateTimeRange](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isValidDateTimeRange.md): Return true if `value1` and `value2` form a valid datetime range — both parseable as
- [isValidDateTimeUnit](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isValidDateTimeUnit.md): Return true when `unit` is a valid DateTimeUnit.
- [isValidDateUnit](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isValidDateUnit.md): Return true when `unit` is a valid DateUnit.
- [isValidIsoDateLike](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isValidIsoDateLike.md): Return true when the input is a valid PlainDate or PlainDateTime ISO string.
- [isValidPlainNowUnit](https://gmt-dox.northguild.workers.dev/reference/plain/get/isValidPlainNowUnit.md)
- [isValidTime](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isValidTime.md): Return true when `value` is a valid ISO PlainTime string.
- [isValidTimeCycleField](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isValidTimeCycleField.md): Return true when `field` is a valid TimeCycleField.
- [isValidTimeDurationUnit](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isValidTimeDurationUnit.md)
- [isValidTimeInterval](https://gmt-dox.northguild.workers.dev/reference/plain/interval/isValidTimeInterval.md): Return true if `start` and `end` form a valid time interval — both parseable as
- [isValidTimeRange](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isValidTimeRange.md): Return true if `value1` and `value2` form a valid time range — both parseable as
- [isValidTimeUnit](https://gmt-dox.northguild.workers.dev/reference/plain/validate/isValidTimeUnit.md): Return true when `unit` is a valid TimeUnit.
- [isWeekend](https://gmt-dox.northguild.workers.dev/reference/plain/compare/isWeekend.md): Return true when `value` falls on a weekend day for `locale`.
- [LocaleNameStyle](https://gmt-dox.northguild.workers.dev/reference/plain/locale/LocaleNameStyle.md): The LocaleNameStyle type.
- [mapDatesInRange](https://gmt-dox.northguild.workers.dev/reference/plain/map/mapDatesInRange.md): Return an array of ISO PlainDate strings between `startDate` and `endDate` inclusive.
- [mapDaysInMonth](https://gmt-dox.northguild.workers.dev/reference/plain/map/mapDaysInMonth.md): Return an array of ISO PlainDate strings for every day in the given year-month.
- [maxDate](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/maxDate.md): Return the latest (maximum) of the given PlainDate values.
- [maxDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/maxDateTime.md): Return the latest (maximum) of the given PlainDateTime values.
- [maxTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/maxTime.md): Return the latest (maximum) of the given PlainTime values.
- [mergeIntervalsDate](https://gmt-dox.northguild.workers.dev/reference/plain/interval/mergeIntervalsDate.md): Collapse a list of date intervals into the minimum set of non-overlapping intervals.
- [mergeIntervalsDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/mergeIntervalsDateTime.md): Collapse a list of datetime intervals into the minimum set of non-overlapping intervals.
- [mergeIntervalsTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/mergeIntervalsTime.md): Collapse a list of time intervals into the minimum set of non-overlapping intervals.
- [minDate](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/minDate.md): Return the earliest (minimum) of the given PlainDate values.
- [minDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/minDateTime.md): Return the earliest (minimum) of the given PlainDateTime values.
- [minTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/minTime.md): Return the earliest (minimum) of the given PlainTime values.
- [nextWeekday](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/nextWeekday.md): Return a PlainDate ISO string for the next occurrence of `dayOfWeek` on or after `value`.
- [NowUnit](https://gmt-dox.northguild.workers.dev/reference/plain/get/NowUnit.md): The NowUnit type.
- [parseDateTimeWithPattern](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseDateTimeWithPattern.md): Parse a datetime string against a caller-supplied token pattern (e.g.
- [parseDateWithPattern](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseDateWithPattern.md): Parse a date string against a caller-supplied token pattern (e.g.
- [parseDayFromDate](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseDayFromDate.md): Return the day of month (1-31) for a given ISO 8601 date string.
- [parseDayFromDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseDayFromDateTime.md): Return the day of month (1-31) for a given ISO 8601 datetime string.
- [parseDayOfWeekFromDate](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseDayOfWeekFromDate.md): Return the day of week (1-7) for a given ISO 8601 date string.
- [parseDayOfWeekFromDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseDayOfWeekFromDateTime.md): Return the day of week (1-7) for a given ISO 8601 datetime string.
- [parseHourFromDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseHourFromDateTime.md): Return the hour (00-23) for a given ISO 8601 datetime string.
- [parseHourFromTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseHourFromTime.md): Return the hour (0-23) for a given ISO 8601 time string.
- [parseMicrosecondFromDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseMicrosecondFromDateTime.md): Return the microsecond (0-999) for a given ISO 8601 datetime string.
- [parseMicrosecondFromTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseMicrosecondFromTime.md): Return the microsecond (0-999) for a given ISO 8601 time string.
- [parseMillisecondFromDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseMillisecondFromDateTime.md): Return the millisecond (0-999) for a given ISO 8601 datetime string.
- [parseMillisecondFromTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseMillisecondFromTime.md): Return the millisecond (0-999) for a given ISO 8601 time string.
- [parseMinuteFromDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseMinuteFromDateTime.md): Return the minute (0-59) for a given ISO 8601 datetime string.
- [parseMinuteFromTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseMinuteFromTime.md): Return the minute (0-59) for a given ISO 8601 time string.
- [parseMonthFromDate](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseMonthFromDate.md): Return the month (1-12) for a given ISO 8601 date string.
- [parseMonthFromDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseMonthFromDateTime.md): Return the month (1-12) for a given ISO 8601 datetime string.
- [parseNanosecondFromDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseNanosecondFromDateTime.md): Return the nanosecond (0-999) for a given ISO 8601 datetime string.
- [parseNanosecondFromTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseNanosecondFromTime.md): Return the nanosecond (0-999) for a given ISO 8601 time string.
- [parseSecondFromDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseSecondFromDateTime.md): Return the second (0-59) for a given ISO 8601 datetime string.
- [parseSecondFromTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseSecondFromTime.md): Return the second (0-59) for a given ISO 8601 time string.
- [parseSql](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseSql.md): Parse an ANSI SQL / ODBC datetime literal — the `YYYY-MM-DD HH:MM:SS` form
- [parseTimeWithPattern](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseTimeWithPattern.md): Parse a time string against a caller-supplied token pattern (e.g.
- [parseUnitFromDate](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseUnitFromDate.md): Return a specific date unit extracted from a PlainDate string.
- [parseUnitFromDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseUnitFromDateTime.md): Return a specific unit extracted from a PlainDateTime string.
- [parseUnitFromTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseUnitFromTime.md): Return a specific time unit extracted from a PlainTime string.
- [parseWeekFromDate](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseWeekFromDate.md): Return the week number for a given ISO 8601 date string.
- [parseWeekFromDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseWeekFromDateTime.md): Return the week number for a given ISO 8601 datetime string.
- [parseYearFromDate](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseYearFromDate.md): Return the year for a given ISO 8601 date string.
- [parseYearFromDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/parse/parseYearFromDateTime.md): Return the year for a given ISO 8601 datetime string.
- [previousWeekday](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/previousWeekday.md): Return a PlainDate ISO string for the previous occurrence of `dayOfWeek` on or before `value`.
- [RelativeUnit](https://gmt-dox.northguild.workers.dev/reference/plain/format/RelativeUnit.md): No "hour"/"minute"/"second" — PlainDate has no time component.
- [roundDate](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/roundDate.md): Round an ISO 8601 date string to the specified date unit.
- [roundDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/roundDateTime.md): Round an ISO 8601 datetime string to the specified date-time unit.
- [roundTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/roundTime.md): Round an ISO 8601 time string to the specified time unit.
- [setDate](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/setDate.md): Return a PlainDate ISO string with the given `fields` set on `value`.
- [setDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/setDateTime.md): Return a PlainDateTime ISO string with the given `fields` set on `value`.
- [setTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/setTime.md): Return a PlainTime ISO string with the given `fields` set on `value`.
- [sortDates](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/sortDates.md): Sort an array of PlainDate values in ascending or descending order.
- [sortDateTimes](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/sortDateTimes.md): Sort an array of PlainDateTime values in ascending or descending order.
- [sortTimes](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/sortTimes.md): Sort an array of PlainTime values in ascending or descending order.
- [splitIntervalByUnitDate](https://gmt-dox.northguild.workers.dev/reference/plain/interval/splitIntervalByUnitDate.md): Split a date interval into sub-intervals of `amount × unit`.
- [splitIntervalByUnitDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/splitIntervalByUnitDateTime.md): Split a date-time interval into sub-intervals of `amount × unit`.
- [splitIntervalByUnitTime](https://gmt-dox.northguild.workers.dev/reference/plain/interval/splitIntervalByUnitTime.md): Split a time interval into sub-intervals of `amount × unit`.
- [startOfDate](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/startOfDate.md): Return the start of the specified date `unit` for a given ISO 8601 date string.
- [startOfDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/startOfDateTime.md): Return the start of the specified date-time `unit` for a given ISO 8601 datetime string.
- [startOfQuarterForDate](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/startOfQuarterForDate.md): Return the first day of the quarter for a given ISO date.
- [startOfQuarterForDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/startOfQuarterForDateTime.md): Return the start of the quarter for a given ISO datetime.
- [startOfTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/startOfTime.md): Return the start of the specified time `unit` for a given ISO 8601 time string.
- [StartOfTimeUnit](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/StartOfTimeUnit.md): The StartOfTimeUnit type.
- [startOfUnit](https://gmt-dox.northguild.workers.dev/reference/plain/interval/startOfUnit.md): Return the start of `unit` for a `Temporal.PlainDateTime`, for every DateTimeUnit.
- [subtractBusinessDays](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/subtractBusinessDays.md): Return a PlainDate ISO string with `amount` business days subtracted from `value`.
- [subtractDate](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/subtractDate.md): Return a PlainDate ISO string with `units` subtracted from `value`.
- [subtractDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/subtractDateTime.md): Return a PlainDateTime ISO string with `units` subtracted from `value`.
- [subtractTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/subtractTime.md): Return a PlainTime ISO string with `units` subtracted from `value`.
- [weekOfYearForDate](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/weekOfYearForDate.md): Return the ISO week number for a given ISO 8601 date string.
- [weekOfYearForDateTime](https://gmt-dox.northguild.workers.dev/reference/plain/calculate/weekOfYearForDateTime.md): Return the ISO week number for a given ISO 8601 datetime string.

## Reference — regex

- [calendarDate](https://gmt-dox.northguild.workers.dev/reference/regex/calendar-date/calendarDate.md): GMT's own calendar-annotated PlainDate string: the calendar-native year/month/day
- [calendarZonedDateTime](https://gmt-dox.northguild.workers.dev/reference/regex/calendar-zoned-date-time/calendarZonedDateTime.md): GMT's own calendar-annotated ZonedDateTime string — the zoned sibling of `calendarDate`
- [day](https://gmt-dox.northguild.workers.dev/reference/regex/date/day.md)
- [fractionalSecond](https://gmt-dox.northguild.workers.dev/reference/regex/time/fractionalSecond.md): regex patterns exported for usage
- [hour](https://gmt-dox.northguild.workers.dev/reference/regex/time/hour.md): regex patterns exported for usage
- [httpDate](https://gmt-dox.northguild.workers.dev/reference/regex/http-date/httpDate.md): RFC 7231 §7.1.1.1 IMF-fixdate — the only form GMT's `formatHttp` emits, and
- [leapSecond](https://gmt-dox.northguild.workers.dev/reference/regex/leap-second/leapSecond.md): ISO 8601 leap second pattern (second = 60)
- [millisecond](https://gmt-dox.northguild.workers.dev/reference/regex/time/millisecond.md): regex patterns exported for usage
- [minute](https://gmt-dox.northguild.workers.dev/reference/regex/time/minute.md): regex patterns exported for usage
- [month](https://gmt-dox.northguild.workers.dev/reference/regex/date/month.md)
- [plainDate](https://gmt-dox.northguild.workers.dev/reference/regex/date/plainDate.md): ISO 8601 calendar date (extended): YYYY-MM-DD or ±YYYYYY-MM-DD
- [plainDateTime](https://gmt-dox.northguild.workers.dev/reference/regex/date-time/plainDateTime.md): ISO 8601 local date-time (extended): <date>T<time>
- [plainTime](https://gmt-dox.northguild.workers.dev/reference/regex/time/plainTime.md): regex patterns exported for usage
- [rfc2822DateTime](https://gmt-dox.northguild.workers.dev/reference/regex/rfc-2822/rfc2822DateTime.md): RFC 5322 §3.3 date-time grammar (obsoletes RFC 2822, same date-time shape).
- [rfc3339DateTime](https://gmt-dox.northguild.workers.dev/reference/regex/rfc-3339/rfc3339DateTime.md): RFC 3339 §5.6 date-time — the same field grammar as ISO 8601 but with a
- [second](https://gmt-dox.northguild.workers.dev/reference/regex/time/second.md): regex patterns exported for usage
- [sqlDateTime](https://gmt-dox.northguild.workers.dev/reference/regex/sql-date-time/sqlDateTime.md): ANSI SQL / ODBC timestamp literal: space-separated (never "T"), always
- [timeZoneLike](https://gmt-dox.northguild.workers.dev/reference/regex/time-zone-like/timeZoneLike.md)
- [unixMilliseconds](https://gmt-dox.northguild.workers.dev/reference/regex/unix/unixMilliseconds.md)
- [unixSeconds](https://gmt-dox.northguild.workers.dev/reference/regex/unix/unixSeconds.md)
- [utcDateTime](https://gmt-dox.northguild.workers.dev/reference/regex/utc-date-time/utcDateTime.md): ISO 8601 UTC datetime: <date>T<time>Z with optional fractional seconds
- [year](https://gmt-dox.northguild.workers.dev/reference/regex/date/year.md)

## Reference — types

- [CalendarSystem](https://gmt-dox.northguild.workers.dev/reference/types/calendar-system/CalendarSystem.md): The set of calendar systems GMT's calendar-conversion functions support. Extended by later Story Group E stories as they land — do not pre-declare identifiers for calendars not yet implemented.
- [DateCycleField](https://gmt-dox.northguild.workers.dev/reference/types/date-cycle-field/DateCycleField.md): the subset of Temporal.PlainDateLike fields that cycleDate/cycleDateTime/cycleZoned can wrap; deliberately narrower than DateUnit, which includes "week" (not a .with()-settable field)
- [DateDurationUnit](https://gmt-dox.northguild.workers.dev/reference/types/date-duration-unit/DateDurationUnit.md): The DateDurationUnit type.
- [DateTimeCycleField](https://gmt-dox.northguild.workers.dev/reference/types/date-time-cycle-field/DateTimeCycleField.md): used by cycleDateTime and cycleZoned, which can cycle either a date or a time field
- [DateTimeDurationUnit](https://gmt-dox.northguild.workers.dev/reference/types/date-time-duration-units/DateTimeDurationUnit.md): The DateTimeDurationUnit type.
- [DateTimeUnit](https://gmt-dox.northguild.workers.dev/reference/types/date-time-unit/DateTimeUnit.md): The DateTimeUnit type.
- [DateUnit](https://gmt-dox.northguild.workers.dev/reference/types/date-unit/DateUnit.md): The DateUnit type.
- [Disambiguation](https://gmt-dox.northguild.workers.dev/reference/types/disambiguation/Disambiguation.md): used in Temporal with methods like Temporal.ZonedDateTime.from(item, { disambiguation })
- [DurationRelativeTo](https://gmt-dox.northguild.workers.dev/reference/types/duration-relative-to/DurationRelativeTo.md): The anchor date a calendar-unit duration operation resolves against, as accepted by Temporal's `relativeTo` option (Duration.prototype.round/.total, Duration.compare). Years/months/weeks have no fixed length, so any operation touching them needs a starting point; day/time-only operations do not.
- [DurationStringOptions](https://gmt-dox.northguild.workers.dev/reference/types/duration-string-options/DurationStringOptions.md): Precision options for Temporal.Duration.prototype.toString(), kept separate from RoundingOptions because both option sets have colliding smallestUnit/roundingMode keys with different Temporal types (DifferenceOptions vs ToStringPrecisionOptions).
- [FractionalDigit](https://gmt-dox.northguild.workers.dev/reference/types/fractional-digit/FractionalDigit.md): used in Temporal with methods like toString({ fractionalSecondDigits: fractionalDigits[unit] })
- [Offset](https://gmt-dox.northguild.workers.dev/reference/types/offset/Offset.md): used alongside disambiguation in Temporal with()/from() methods like Temporal.ZonedDateTime.prototype.with(item, { disambiguation, offset })
- [Overflow](https://gmt-dox.northguild.workers.dev/reference/types/overflow/Overflow.md): used in Temporal add()/subtract() methods like Temporal.PlainDate.prototype.add(item, { overflow })
- [RelativeRoundingMethod](https://gmt-dox.northguild.workers.dev/reference/types/relative-rounding-method/RelativeRoundingMethod.md): Used by the formatRelative* family — how the computed distance rounds to the display unit, applied to the signed fractional value (see internal/resolveRelativeRounding.ts).
- [RoundingOptions](https://gmt-dox.northguild.workers.dev/reference/types/rounding-options/RoundingOptions.md): used in Temporal until()/since() methods like Temporal.PlainDate.prototype.until(other, options)
- [TimeCycleField](https://gmt-dox.northguild.workers.dev/reference/types/time-cycle-field/TimeCycleField.md): the subset of Temporal.PlainTimeLike fields that cycleTime/cycleDateTime/cycleZoned can wrap; goes to nanosecond precision, wider than @internationalized/date's Time (millisecond ceiling), since GMT's PlainTime and setTime already support the full range
- [TimeDurationUnit](https://gmt-dox.northguild.workers.dev/reference/types/time-duration-unit/TimeDurationUnit.md): The TimeDurationUnit type.
- [TimeUnit](https://gmt-dox.northguild.workers.dev/reference/types/time-unit/TimeUnit.md): The TimeUnit type.

## Reference — unix

- [addUnix](https://gmt-dox.northguild.workers.dev/reference/unix/calculate/addUnix.md): Add a temporal amount to a Unix epoch value and return the resulting epoch.
- [areUnixEqual](https://gmt-dox.northguild.workers.dev/reference/unix/compare/areUnixEqual.md): Return whether `value1` and `value2` represent the same instant.
- [areUnixEqualBy](https://gmt-dox.northguild.workers.dev/reference/unix/compare/areUnixEqualBy.md): Compare two Unix epoch values for equality at a given unit.
- [convertUnixToPlainDate](https://gmt-dox.northguild.workers.dev/reference/unix/convert/convertUnixToPlainDate.md): Convert a Unix timestamp to a plain date string in the format "YYYY-MM-DD".
- [convertUnixToPlainDateTime](https://gmt-dox.northguild.workers.dev/reference/unix/convert/convertUnixToPlainDateTime.md): Convert a Unix timestamp to a plain datetime string in the format "YYYY-MM-DDTHH:mm:ss".
- [convertUnixToPlainTime](https://gmt-dox.northguild.workers.dev/reference/unix/convert/convertUnixToPlainTime.md): Convert a Unix timestamp to a plain time string in the format "HH:mm:ss".
- [convertUnixToUtc](https://gmt-dox.northguild.workers.dev/reference/unix/convert/convertUnixToUtc.md): Convert a unix epoch value to a UTC Instant ISO string.
- [convertUnixToZoned](https://gmt-dox.northguild.workers.dev/reference/unix/convert/convertUnixToZoned.md): Convert a unix epoch value to a zoned ISO 8601 datetime string.
- [diffUnix](https://gmt-dox.northguild.workers.dev/reference/unix/calculate/diffUnix.md): Return the difference between two Unix timestamps measured in the given unit.
- [diffUnixAsDuration](https://gmt-dox.northguild.workers.dev/reference/unix/calculate/diffUnixAsDuration.md): Return the difference between two Unix timestamps as an ISO 8601 duration string,
- [endOfQuarterForUnix](https://gmt-dox.northguild.workers.dev/reference/unix/calculate/endOfQuarterForUnix.md): Return the end of the quarter for a Unix timestamp.
- [endOfUnix](https://gmt-dox.northguild.workers.dev/reference/unix/calculate/endOfUnix.md): Return the end of the specified unit for a Unix timestamp.
- [formatCalendarUnix](https://gmt-dox.northguild.workers.dev/reference/unix/format/formatCalendarUnix.md): Format a unix epoch value as a relative day label plus time-of-day, e.g.
- [FormatCalendarUnixOptions](https://gmt-dox.northguild.workers.dev/reference/unix/format/FormatCalendarUnixOptions.md): The FormatCalendarUnixOptions type.
- [formatRelativeUnix](https://gmt-dox.northguild.workers.dev/reference/unix/format/formatRelativeUnix.md): Format the relative time between a unix epoch value and a reference instant.
- [FormatRelativeUnixOptions](https://gmt-dox.northguild.workers.dev/reference/unix/format/FormatRelativeUnixOptions.md): The FormatRelativeUnixOptions type.
- [formatUnix](https://gmt-dox.northguild.workers.dev/reference/unix/format/formatUnix.md): Format a unix epoch value (string or number) as a localized date/time string.
- [FormatUnixOptions](https://gmt-dox.northguild.workers.dev/reference/unix/format/FormatUnixOptions.md): The FormatUnixOptions type.
- [getUnixDay](https://gmt-dox.northguild.workers.dev/reference/unix/get/getUnixDay.md): Return the current day from the Unix timestamp in UTC as a zero-padded string.
- [getUnixHour](https://gmt-dox.northguild.workers.dev/reference/unix/get/getUnixHour.md): Return the current hour from the Unix timestamp in UTC as a zero-padded string.
- [getUnixMicrosecond](https://gmt-dox.northguild.workers.dev/reference/unix/get/getUnixMicrosecond.md): Return the current microsecond from the Unix timestamp in UTC as a zero-padded string.
- [getUnixMillisecond](https://gmt-dox.northguild.workers.dev/reference/unix/get/getUnixMillisecond.md): Return the current millisecond from the Unix timestamp in UTC as a zero-padded string.
- [getUnixMinute](https://gmt-dox.northguild.workers.dev/reference/unix/get/getUnixMinute.md): Return the current minute from the Unix timestamp in UTC as a zero-padded string.
- [getUnixMonth](https://gmt-dox.northguild.workers.dev/reference/unix/get/getUnixMonth.md): Return the current month from the Unix timestamp in UTC as a zero-padded string.
- [getUnixNanosecond](https://gmt-dox.northguild.workers.dev/reference/unix/get/getUnixNanosecond.md): Return the current nanosecond from the Unix timestamp in UTC as a zero-padded string.
- [getUnixNow](https://gmt-dox.northguild.workers.dev/reference/unix/get/getUnixNow.md): Return the current Unix timestamp in either seconds or milliseconds.
- [getUnixNowUnit](https://gmt-dox.northguild.workers.dev/reference/unix/get/getUnixNowUnit.md): Return the requested unit value from the current Unix timestamp in UTC.
- [getUnixSecond](https://gmt-dox.northguild.workers.dev/reference/unix/get/getUnixSecond.md): Return the current second from the Unix timestamp in UTC as a zero-padded string.
- [getUnixYear](https://gmt-dox.northguild.workers.dev/reference/unix/get/getUnixYear.md): Return the current year from the Unix timestamp in UTC as a zero-padded string.
- [intervalAbutsUnix](https://gmt-dox.northguild.workers.dev/reference/unix/interval/intervalAbutsUnix.md): Return true when two Unix intervals are exactly adjacent — one's end equals the other's
- [intervalContainsUnix](https://gmt-dox.northguild.workers.dev/reference/unix/interval/intervalContainsUnix.md): Return true when `pointOrStart` falls within the interval `[intervalStart, intervalEnd]`
- [intervalCountUnix](https://gmt-dox.northguild.workers.dev/reference/unix/interval/intervalCountUnix.md): Count how many `unit` boundaries a Unix epoch interval crosses.
- [intervalDifferenceUnix](https://gmt-dox.northguild.workers.dev/reference/unix/interval/intervalDifferenceUnix.md): Return the portion(s) of interval A not covered by interval B.
- [intervalDivideEquallyUnix](https://gmt-dox.northguild.workers.dev/reference/unix/interval/intervalDivideEquallyUnix.md): Split a Unix epoch interval into `n` equal-length sub-intervals.
- [intervalEngulfsUnix](https://gmt-dox.northguild.workers.dev/reference/unix/interval/intervalEngulfsUnix.md): Return true when interval B is fully contained within interval A — every instant of B
- [intervalFromDurationUnix](https://gmt-dox.northguild.workers.dev/reference/unix/interval/intervalFromDurationUnix.md): Construct a Unix epoch interval from a single point plus an ISO 8601 duration, anchored at either end.
- [intervalIntersectionUnix](https://gmt-dox.northguild.workers.dev/reference/unix/interval/intervalIntersectionUnix.md): Return the overlapping span of two Unix epoch intervals, or null when they do not overlap.
- [intervalLengthUnix](https://gmt-dox.northguild.workers.dev/reference/unix/interval/intervalLengthUnix.md): Return the exact length of a Unix epoch interval in `unit`, as a real (possibly fractional) number.
- [intervalOverlappingDaysUnix](https://gmt-dox.northguild.workers.dev/reference/unix/interval/intervalOverlappingDaysUnix.md): Return how many distinct calendar dates two Unix epoch intervals share, in a given
- [intervalsOverlapUnix](https://gmt-dox.northguild.workers.dev/reference/unix/interval/intervalsOverlapUnix.md): Return true when intervals `[aStart, aEnd]` and `[bStart, bEnd]` share at least one instant.
- [intervalSplitAtUnix](https://gmt-dox.northguild.workers.dev/reference/unix/interval/intervalSplitAtUnix.md): Split a Unix epoch interval at arbitrary `points`, producing consecutive sub-intervals.
- [intervalUnionUnix](https://gmt-dox.northguild.workers.dev/reference/unix/interval/intervalUnionUnix.md): Return the combined span of two Unix epoch intervals, or null when they are disjoint.
- [intervalXorAllUnix](https://gmt-dox.northguild.workers.dev/reference/unix/interval/intervalXorAllUnix.md): Return the symmetric difference across a list of Unix epoch intervals — the set of epoch
- [intervalXorUnix](https://gmt-dox.northguild.workers.dev/reference/unix/interval/intervalXorUnix.md): Return the symmetric difference of two Unix intervals — time covered by exactly one interval.
- [isAfterUnix](https://gmt-dox.northguild.workers.dev/reference/unix/compare/isAfterUnix.md): Return whether `value1` represents an instant strictly after `value2`.
- [isBeforeUnix](https://gmt-dox.northguild.workers.dev/reference/unix/compare/isBeforeUnix.md): Return whether `value1` represents an instant strictly before `value2`.
- [isBetweenUnix](https://gmt-dox.northguild.workers.dev/reference/unix/calculate/isBetweenUnix.md): Return true when the Unix timestamp is between start and end (inclusive by default).
- [isValidUnixInterval](https://gmt-dox.northguild.workers.dev/reference/unix/interval/isValidUnixInterval.md): Return true if `start` and `end` form a valid Unix interval — both finite numbers
- [isValidUnixMilliseconds](https://gmt-dox.northguild.workers.dev/reference/unix/validate/isValidUnixMilliseconds.md): Return true when `timestamp` is a valid Unix milliseconds value.
- [isValidUnixNowUnit](https://gmt-dox.northguild.workers.dev/reference/unix/get/isValidUnixNowUnit.md)
- [isValidUnixRange](https://gmt-dox.northguild.workers.dev/reference/unix/validate/isValidUnixRange.md): Return true if `value1` and `value2` form a valid Unix range — both finite numbers
- [isValidUnixSeconds](https://gmt-dox.northguild.workers.dev/reference/unix/validate/isValidUnixSeconds.md): Return true when `timestamp` is a valid Unix seconds value.
- [isValidUnixUnit](https://gmt-dox.northguild.workers.dev/reference/unix/validate/isValidUnixUnit.md): Return true when `unit` is a valid UnixUnit.
- [maxUnix](https://gmt-dox.northguild.workers.dev/reference/unix/calculate/maxUnix.md): Return the latest (maximum) of the given Unix timestamp values.
- [mergeIntervalsUnix](https://gmt-dox.northguild.workers.dev/reference/unix/interval/mergeIntervalsUnix.md): Collapse a list of Unix epoch intervals into the minimum set of non-overlapping intervals.
- [minUnix](https://gmt-dox.northguild.workers.dev/reference/unix/calculate/minUnix.md): Return the earliest (minimum) of the given Unix timestamp values.
- [parseDateFromUnix](https://gmt-dox.northguild.workers.dev/reference/unix/parse/parseDateFromUnix.md): Extract the date portion from a unix epoch value.
- [parseDayFromUnix](https://gmt-dox.northguild.workers.dev/reference/unix/parse/parseDayFromUnix.md): Return the day of month (1-31) from a unix epoch value.
- [parseDayOfWeekFromUnix](https://gmt-dox.northguild.workers.dev/reference/unix/parse/parseDayOfWeekFromUnix.md): Return the day of week (1-7) from a unix epoch value.
- [parseEpochMs](https://gmt-dox.northguild.workers.dev/reference/unix/format/parseEpochMs.md)
- [parseHourFromUnix](https://gmt-dox.northguild.workers.dev/reference/unix/parse/parseHourFromUnix.md): Return the hour (0-23) from a unix epoch value.
- [parseMicrosecondFromUnix](https://gmt-dox.northguild.workers.dev/reference/unix/parse/parseMicrosecondFromUnix.md): Return the microsecond (0-999) from a unix epoch value.
- [parseMillisecondFromUnix](https://gmt-dox.northguild.workers.dev/reference/unix/parse/parseMillisecondFromUnix.md): Return the millisecond (0-999) from a unix epoch value.
- [parseMinuteFromUnix](https://gmt-dox.northguild.workers.dev/reference/unix/parse/parseMinuteFromUnix.md): Return the minute (0-59) from a unix epoch value.
- [parseMonthFromUnix](https://gmt-dox.northguild.workers.dev/reference/unix/parse/parseMonthFromUnix.md): Return the month (1-12) from a unix epoch value.
- [parseNanosecondFromUnix](https://gmt-dox.northguild.workers.dev/reference/unix/parse/parseNanosecondFromUnix.md): Return the nanosecond (0-999) from a unix epoch value.
- [parseSecondFromUnix](https://gmt-dox.northguild.workers.dev/reference/unix/parse/parseSecondFromUnix.md): Return the second (0-59) from a unix epoch value.
- [parseTimeFromUnix](https://gmt-dox.northguild.workers.dev/reference/unix/parse/parseTimeFromUnix.md): Extract the time portion from a unix epoch value.
- [parseUnitFromUnix](https://gmt-dox.northguild.workers.dev/reference/unix/parse/parseUnitFromUnix.md): Extract a unit from a unix epoch value.
- [parseWeekFromUnix](https://gmt-dox.northguild.workers.dev/reference/unix/parse/parseWeekFromUnix.md): Return the week number from a unix epoch value.
- [parseYearFromUnix](https://gmt-dox.northguild.workers.dev/reference/unix/parse/parseYearFromUnix.md): Return the year from a unix epoch value.
- [PlainNowUnit](https://gmt-dox.northguild.workers.dev/reference/unix/parse/PlainNowUnit.md): The PlainNowUnit type.
- [RelativeUnit](https://gmt-dox.northguild.workers.dev/reference/unix/format/RelativeUnit.md): Intl.RelativeTimeFormatUnit includes "quarter" which Temporal doesn't support.
- [ResolvedUnixInterval](https://gmt-dox.northguild.workers.dev/reference/unix/interval/ResolvedUnixInterval.md): The ResolvedUnixInterval type.
- [resolveUnixIntervalPair](https://gmt-dox.northguild.workers.dev/reference/unix/interval/resolveUnixIntervalPair.md)
- [roundUnix](https://gmt-dox.northguild.workers.dev/reference/unix/calculate/roundUnix.md): Round a Unix timestamp to the specified unit.
- [setUnix](https://gmt-dox.northguild.workers.dev/reference/unix/calculate/setUnix.md): Return a Unix epoch value with the given `fields` set on `value`, interpreted in `timeZone`.
- [sortUnix](https://gmt-dox.northguild.workers.dev/reference/unix/calculate/sortUnix.md): Sort an array of Unix timestamp values in ascending or descending order.
- [splitIntervalByUnitUnix](https://gmt-dox.northguild.workers.dev/reference/unix/interval/splitIntervalByUnitUnix.md): Split a Unix epoch interval into sub-intervals of `amount × unit`.
- [startOfQuarterForUnix](https://gmt-dox.northguild.workers.dev/reference/unix/calculate/startOfQuarterForUnix.md): Return the start of the quarter for a Unix timestamp.
- [startOfUnix](https://gmt-dox.northguild.workers.dev/reference/unix/calculate/startOfUnix.md): Return the start of the specified unit for a Unix timestamp.
- [startOrEndOfUnix](https://gmt-dox.northguild.workers.dev/reference/unix/calculate/startOrEndOfUnix.md): Internal shared implementation for `startOfUnix` / `endOfUnix`.
- [subtractUnix](https://gmt-dox.northguild.workers.dev/reference/unix/calculate/subtractUnix.md): Subtract a temporal amount from a Unix epoch value and return the resulting epoch.
- [toInstant](https://gmt-dox.northguild.workers.dev/reference/unix/format/toInstant.md)
- [UnixNowUnit](https://gmt-dox.northguild.workers.dev/reference/unix/get/UnixNowUnit.md): The UnixNowUnit type.
- [UnixUnit](https://gmt-dox.northguild.workers.dev/reference/unix/validate/UnixUnit.md): The UnixUnit type.

## Reference — utc

- [addUtc](https://gmt-dox.northguild.workers.dev/reference/utc/calculate/addUtc.md): Add a temporal amount to a UTC datetime string and return a new UTC Instant string.
- [areUtcEqual](https://gmt-dox.northguild.workers.dev/reference/utc/compare/areUtcEqual.md): Return whether `value1` and `value2` represent the same instant.
- [areUtcEqualBy](https://gmt-dox.northguild.workers.dev/reference/utc/compare/areUtcEqualBy.md): Compare two UTC ISO datetime strings for equality at a given unit.
- [chopUtc](https://gmt-dox.northguild.workers.dev/reference/utc/chop/chopUtc.md): Return the UTC datetime string with a trailing Z removed if present.
- [convertUtcToPlainDate](https://gmt-dox.northguild.workers.dev/reference/utc/convert/convertUtcToPlainDate.md): Convert a UTC datetime string to a plain date string in the format "YYYY-MM-DD".
- [convertUtcToPlainDateTime](https://gmt-dox.northguild.workers.dev/reference/utc/convert/convertUtcToPlainDateTime.md): Convert a UTC datetime string to a plain datetime string in the format "YYYY-MM-DDTHH:mm:ss".
- [convertUtcToPlainTime](https://gmt-dox.northguild.workers.dev/reference/utc/convert/convertUtcToPlainTime.md): Convert a UTC datetime string to a plain time string in the format "HH:mm:ss".
- [convertUtcToUnix](https://gmt-dox.northguild.workers.dev/reference/utc/convert/convertUtcToUnix.md): Convert a UTC Instant string to a unix epoch value in milliseconds or seconds.
- [convertUtcToZoned](https://gmt-dox.northguild.workers.dev/reference/utc/convert/convertUtcToZoned.md): Convert a UTC Instant string to a zoned ISO 8601 datetime string.
- [diffUtc](https://gmt-dox.northguild.workers.dev/reference/utc/calculate/diffUtc.md): Return the difference between two UTC datetimes measured in the given date-time unit.
- [diffUtcAsDuration](https://gmt-dox.northguild.workers.dev/reference/utc/calculate/diffUtcAsDuration.md): Return the difference between two UTC datetimes as an ISO 8601 duration string,
- [endOfQuarterForUtc](https://gmt-dox.northguild.workers.dev/reference/utc/calculate/endOfQuarterForUtc.md): Return the end of the quarter for a given UTC Instant string.
- [endOfUtc](https://gmt-dox.northguild.workers.dev/reference/utc/calculate/endOfUtc.md): Return the end of the specified date-time `unit` for a given UTC datetime string.
- [formatCalendarUtc](https://gmt-dox.northguild.workers.dev/reference/utc/format/formatCalendarUtc.md): Format a UTC ISO string as a relative day label plus time-of-day, e.g.
- [FormatCalendarUtcOptions](https://gmt-dox.northguild.workers.dev/reference/utc/format/FormatCalendarUtcOptions.md): The FormatCalendarUtcOptions type.
- [formatHttp](https://gmt-dox.northguild.workers.dev/reference/utc/format/formatHttp.md): Format a UTC ISO 8601 datetime string as an RFC 7231 IMF-fixdate — the
- [formatRelativeUtc](https://gmt-dox.northguild.workers.dev/reference/utc/format/formatRelativeUtc.md): Format the relative time between a UTC ISO string and a reference instant.
- [FormatRelativeUtcOptions](https://gmt-dox.northguild.workers.dev/reference/utc/format/FormatRelativeUtcOptions.md): The FormatRelativeUtcOptions type.
- [formatUtc](https://gmt-dox.northguild.workers.dev/reference/utc/format/formatUtc.md): Format a UTC ISO string as a localized date/time string.
- [FormatUtcOptions](https://gmt-dox.northguild.workers.dev/reference/utc/format/FormatUtcOptions.md): The FormatUtcOptions type.
- [getUtcDay](https://gmt-dox.northguild.workers.dev/reference/utc/get/getUtcDay.md): Return the current day from UTC as a zero-padded string.
- [getUtcHour](https://gmt-dox.northguild.workers.dev/reference/utc/get/getUtcHour.md): Return the current hour from UTC as a zero-padded string.
- [getUtcMicrosecond](https://gmt-dox.northguild.workers.dev/reference/utc/get/getUtcMicrosecond.md): Return the current microsecond from UTC as a zero-padded string.
- [getUtcMillisecond](https://gmt-dox.northguild.workers.dev/reference/utc/get/getUtcMillisecond.md): Return the current millisecond from UTC as a zero-padded string.
- [getUtcMinute](https://gmt-dox.northguild.workers.dev/reference/utc/get/getUtcMinute.md): Return the current minute from UTC as a zero-padded string.
- [getUtcMonth](https://gmt-dox.northguild.workers.dev/reference/utc/get/getUtcMonth.md): Return the current month from UTC as a zero-padded string.
- [getUtcNanosecond](https://gmt-dox.northguild.workers.dev/reference/utc/get/getUtcNanosecond.md): Return the current nanosecond from UTC as a zero-padded string.
- [getUtcNow](https://gmt-dox.northguild.workers.dev/reference/utc/get/getUtcNow.md): Return the current UTC instant as an ISO Instant string.
- [getUtcNowUnit](https://gmt-dox.northguild.workers.dev/reference/utc/get/getUtcNowUnit.md): Return the requested unit value from the current UTC instant.
- [getUtcSecond](https://gmt-dox.northguild.workers.dev/reference/utc/get/getUtcSecond.md): Return the current second from UTC as a zero-padded string.
- [getUtcYear](https://gmt-dox.northguild.workers.dev/reference/utc/get/getUtcYear.md): Return the current year from UTC as a zero-padded string.
- [intervalAbutsUtc](https://gmt-dox.northguild.workers.dev/reference/utc/interval/intervalAbutsUtc.md): Return true when two UTC intervals are exactly adjacent — one's end equals the other's
- [intervalContainsUtc](https://gmt-dox.northguild.workers.dev/reference/utc/interval/intervalContainsUtc.md): Return true when `pointOrStart` falls within the interval `[intervalStart, intervalEnd]`
- [intervalCountUtc](https://gmt-dox.northguild.workers.dev/reference/utc/interval/intervalCountUtc.md): Count how many `unit` boundaries a UTC interval crosses.
- [intervalDifferenceUtc](https://gmt-dox.northguild.workers.dev/reference/utc/interval/intervalDifferenceUtc.md): Return the portion(s) of interval A not covered by interval B.
- [intervalDivideEquallyUtc](https://gmt-dox.northguild.workers.dev/reference/utc/interval/intervalDivideEquallyUtc.md): Split a UTC interval into `n` equal-length sub-intervals.
- [intervalEngulfsUtc](https://gmt-dox.northguild.workers.dev/reference/utc/interval/intervalEngulfsUtc.md): Return true when interval B is fully contained within interval A — every instant of B
- [intervalFromDurationUtc](https://gmt-dox.northguild.workers.dev/reference/utc/interval/intervalFromDurationUtc.md): Construct a UTC interval from a single point plus an ISO 8601 duration, anchored at either end.
- [intervalIntersectionUtc](https://gmt-dox.northguild.workers.dev/reference/utc/interval/intervalIntersectionUtc.md): Return the overlapping span of two UTC intervals, or null when they do not overlap.
- [intervalLengthUtc](https://gmt-dox.northguild.workers.dev/reference/utc/interval/intervalLengthUtc.md): Return the exact length of a UTC interval in `unit`, as a real (possibly fractional) number.
- [intervalOverlappingDaysUtc](https://gmt-dox.northguild.workers.dev/reference/utc/interval/intervalOverlappingDaysUtc.md): Return how many distinct UTC calendar dates two UTC intervals share.
- [intervalsOverlapUtc](https://gmt-dox.northguild.workers.dev/reference/utc/interval/intervalsOverlapUtc.md): Return true when intervals `[aStart, aEnd]` and `[bStart, bEnd]` share at least one instant.
- [intervalSplitAtUtc](https://gmt-dox.northguild.workers.dev/reference/utc/interval/intervalSplitAtUtc.md): Split a UTC interval at arbitrary `points`, producing consecutive sub-intervals.
- [intervalUnionUtc](https://gmt-dox.northguild.workers.dev/reference/utc/interval/intervalUnionUtc.md): Return the combined span of two UTC intervals, or null when they are disjoint.
- [intervalXorAllUtc](https://gmt-dox.northguild.workers.dev/reference/utc/interval/intervalXorAllUtc.md): Return the symmetric difference across a list of UTC intervals — the set of instants covered
- [intervalXorUtc](https://gmt-dox.northguild.workers.dev/reference/utc/interval/intervalXorUtc.md): Return the symmetric difference of two UTC intervals — time covered by exactly one interval.
- [isAfterUtc](https://gmt-dox.northguild.workers.dev/reference/utc/compare/isAfterUtc.md): Return whether `value1` represents an instant strictly after `value2`.
- [isBeforeUtc](https://gmt-dox.northguild.workers.dev/reference/utc/compare/isBeforeUtc.md): Return whether `value1` represents an instant strictly before `value2`.
- [isBetweenUtc](https://gmt-dox.northguild.workers.dev/reference/utc/calculate/isBetweenUtc.md): Return true when `value` is between `start` and `end` (inclusive by default).
- [isValidUtc](https://gmt-dox.northguild.workers.dev/reference/utc/validate/isValidUtc.md): Return true when the provided string is a valid ISO 8601 UTC datetime.
- [isValidUtcInterval](https://gmt-dox.northguild.workers.dev/reference/utc/interval/isValidUtcInterval.md): Return true if `start` and `end` form a valid UTC interval — both parseable as
- [isValidUtcNowUnit](https://gmt-dox.northguild.workers.dev/reference/utc/get/isValidUtcNowUnit.md)
- [isValidUtcRange](https://gmt-dox.northguild.workers.dev/reference/utc/validate/isValidUtcRange.md): Return true if `value1` and `value2` form a valid UTC range — both parseable as
- [maxUtc](https://gmt-dox.northguild.workers.dev/reference/utc/calculate/maxUtc.md): Return the latest (maximum) of the given UTC datetime values.
- [mergeIntervalsUtc](https://gmt-dox.northguild.workers.dev/reference/utc/interval/mergeIntervalsUtc.md): Collapse a list of UTC intervals into the minimum set of non-overlapping intervals.
- [minUtc](https://gmt-dox.northguild.workers.dev/reference/utc/calculate/minUtc.md): Return the earliest (minimum) of the given UTC datetime values.
- [parseDateFromUtc](https://gmt-dox.northguild.workers.dev/reference/utc/parse/parseDateFromUtc.md): Extract the date portion from a UTC datetime string.
- [parseDayFromUtc](https://gmt-dox.northguild.workers.dev/reference/utc/parse/parseDayFromUtc.md): Return the day of month (1-31) from a UTC datetime string.
- [parseDayOfWeekFromUtc](https://gmt-dox.northguild.workers.dev/reference/utc/parse/parseDayOfWeekFromUtc.md): Return the day of week (1-7) from a UTC datetime string.
- [parseHourFromUtc](https://gmt-dox.northguild.workers.dev/reference/utc/parse/parseHourFromUtc.md): Return the hour (0-23) from a UTC datetime string.
- [parseHttp](https://gmt-dox.northguild.workers.dev/reference/utc/parse/parseHttp.md): Parse an RFC 7231 IMF-fixdate string — the fixed grammar HTTP headers like
- [parseMicrosecondFromUtc](https://gmt-dox.northguild.workers.dev/reference/utc/parse/parseMicrosecondFromUtc.md): Return the microsecond (0-999) from a UTC datetime string.
- [parseMillisecondFromUtc](https://gmt-dox.northguild.workers.dev/reference/utc/parse/parseMillisecondFromUtc.md): Return the millisecond (0-999) from a UTC datetime string.
- [parseMinuteFromUtc](https://gmt-dox.northguild.workers.dev/reference/utc/parse/parseMinuteFromUtc.md): Return the minute (0-59) from a UTC datetime string.
- [parseMonthFromUtc](https://gmt-dox.northguild.workers.dev/reference/utc/parse/parseMonthFromUtc.md): Return the month (1-12) from a UTC datetime string.
- [parseNanosecondFromUtc](https://gmt-dox.northguild.workers.dev/reference/utc/parse/parseNanosecondFromUtc.md): Return the nanosecond (0-999) from a UTC datetime string.
- [parseSecondFromUtc](https://gmt-dox.northguild.workers.dev/reference/utc/parse/parseSecondFromUtc.md): Return the second (0-59) from a UTC datetime string.
- [parseTimeFromUtc](https://gmt-dox.northguild.workers.dev/reference/utc/parse/parseTimeFromUtc.md): Extract the time portion from a UTC datetime string.
- [parseUnitFromUtc](https://gmt-dox.northguild.workers.dev/reference/utc/parse/parseUnitFromUtc.md): Extract a unit from a UTC datetime string.
- [parseWeekFromUtc](https://gmt-dox.northguild.workers.dev/reference/utc/parse/parseWeekFromUtc.md): Return the week number from a UTC datetime string.
- [parseYearFromUtc](https://gmt-dox.northguild.workers.dev/reference/utc/parse/parseYearFromUtc.md): Return the year from a UTC datetime string.
- [RelativeUnit](https://gmt-dox.northguild.workers.dev/reference/utc/format/RelativeUnit.md): Intl.RelativeTimeFormatUnit includes "quarter" which Temporal doesn't support.
- [roundUtc](https://gmt-dox.northguild.workers.dev/reference/utc/calculate/roundUtc.md): Round a UTC datetime string to the specified unit.
- [setUtc](https://gmt-dox.northguild.workers.dev/reference/utc/calculate/setUtc.md): Return a UTC Instant string with the given `fields` set on `value`.
- [sortUtc](https://gmt-dox.northguild.workers.dev/reference/utc/calculate/sortUtc.md): Sort an array of UTC datetime values in ascending or descending order.
- [splitIntervalByUnitUtc](https://gmt-dox.northguild.workers.dev/reference/utc/interval/splitIntervalByUnitUtc.md): Split a UTC interval into sub-intervals of `amount × unit`.
- [startOfQuarterForUtc](https://gmt-dox.northguild.workers.dev/reference/utc/calculate/startOfQuarterForUtc.md): Return the start of the quarter for a given UTC datetime string.
- [startOfUtc](https://gmt-dox.northguild.workers.dev/reference/utc/calculate/startOfUtc.md): Return the start of the specified date-time `unit` for a given UTC datetime string.
- [startOrEndOfUtc](https://gmt-dox.northguild.workers.dev/reference/utc/calculate/startOrEndOfUtc.md): Internal shared implementation for `startOfUtc` / `endOfUtc`.
- [subtractUtc](https://gmt-dox.northguild.workers.dev/reference/utc/calculate/subtractUtc.md): Subtract a temporal amount from a UTC datetime string and return a new UTC Instant string.
- [UtcNowUnit](https://gmt-dox.northguild.workers.dev/reference/utc/get/UtcNowUnit.md): The UtcNowUnit type.
- [UtcUnit](https://gmt-dox.northguild.workers.dev/reference/utc/parse/UtcUnit.md): The UtcUnit type.

## Reference — zoned

- [addZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/addZoned.md): Add a temporal amount to a zoned ISO 8601 datetime string and return a zoned ISO 8601 string.
- [addZonedBusinessDays](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/addZonedBusinessDays.md): Return a zoned ISO 8601 datetime string with `amount` business days added to `value`.
- [areZonedEqual](https://gmt-dox.northguild.workers.dev/reference/zoned/compare/areZonedEqual.md): Compare two zoned datetime strings for exact local-field equality.
- [areZonedEqualBy](https://gmt-dox.northguild.workers.dev/reference/zoned/compare/areZonedEqualBy.md): Compare two zoned ISO datetime strings for equality at a given unit.
- [chopZonedDate](https://gmt-dox.northguild.workers.dev/reference/zoned/chop/chopZonedDate.md): Extracts the local time portion from an ISO 8601 zoned datetime string.
- [chopZonedDateTime](https://gmt-dox.northguild.workers.dev/reference/zoned/chop/chopZonedDateTime.md): Extracts the IANA timeZone identifier from an ISO 8601 zoned datetime string.
- [chopZonedMilliseconds](https://gmt-dox.northguild.workers.dev/reference/zoned/chop/chopZonedMilliseconds.md): Returns the zoned datetime string rounded/truncated to second precision.
- [chopZonedSeconds](https://gmt-dox.northguild.workers.dev/reference/zoned/chop/chopZonedSeconds.md): Returns the zoned datetime string truncated to minute precision.
- [chopZonedTime](https://gmt-dox.northguild.workers.dev/reference/zoned/chop/chopZonedTime.md): Extracts the local date portion from an ISO 8601 zoned datetime string.
- [chopZonedTimezone](https://gmt-dox.northguild.workers.dev/reference/zoned/chop/chopZonedTimezone.md): Returns the local plain datetime (date + time) extracted from a zoned datetime string.
- [clampZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/clampZoned.md): Restrict `value` to the range [`min`, `max`] in zoned datetime space.
- [closestZonedTo](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/closestZonedTo.md): Return the candidate zoned datetime nearest to `target` by temporal distance.
- [convertPlainDateTimeToZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/convert/convertPlainDateTimeToZoned.md): Attach the specified `timeZone` to a plain datetime string and return a zoned ISO 8601 datetime string.
- [convertZonedToCalendar](https://gmt-dox.northguild.workers.dev/reference/zoned/convert/convertZonedToCalendar.md): Convert a zoned datetime to the same instant expressed in a different calendar system.
- [convertZonedToPlainDateTime](https://gmt-dox.northguild.workers.dev/reference/zoned/convert/convertZonedToPlainDateTime.md): Convert a zoned ISO 8601 datetime string to a plain datetime string.
- [convertZonedToUnix](https://gmt-dox.northguild.workers.dev/reference/zoned/convert/convertZonedToUnix.md): Convert an ISO 8601 zoned datetime string to a unix epoch value in milliseconds (default) or seconds.
- [convertZonedToUtc](https://gmt-dox.northguild.workers.dev/reference/zoned/convert/convertZonedToUtc.md): Convert an ISO 8601 zoned datetime string to a UTC Instant string (ISO).
- [convertZonedToZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/convert/convertZonedToZoned.md): Convert a zoned ISO 8601 datetime string to the same instant in a different `timeZone`.
- [cycleZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/cycleZoned.md): Return a ZonedDateTime ISO string with `field` cycled by `amount`, wrapping at that field's own
- [diffZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/diffZoned.md): Return the difference between two zoned datetimes measured in the given date-time unit.
- [diffZonedAsDuration](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/diffZonedAsDuration.md): Return the difference between two zoned datetimes as an ISO 8601 duration string,
- [DstTransition](https://gmt-dox.northguild.workers.dev/reference/zoned/get/DstTransition.md): The DstTransition type.
- [endOfQuarterForZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/endOfQuarterForZoned.md): Return the end of the quarter for a given zoned ISO datetime.
- [endOfZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/endOfZoned.md): Return the end of the specified date-time `unit` for a given zoned ISO 8601 datetime string.
- [formatCalendarZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/format/formatCalendarZoned.md): Format a zoned date-time as a relative day label plus time-of-day, e.g.
- [FormatCalendarZonedOptions](https://gmt-dox.northguild.workers.dev/reference/zoned/format/FormatCalendarZonedOptions.md): The FormatCalendarZonedOptions type.
- [formatRelativeZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/format/formatRelativeZoned.md): Format the relative time between a zoned date-time and a reference instant.
- [FormatRelativeZonedOptions](https://gmt-dox.northguild.workers.dev/reference/zoned/format/FormatRelativeZonedOptions.md): The FormatRelativeZonedOptions type.
- [formatRfc2822](https://gmt-dox.northguild.workers.dev/reference/zoned/format/formatRfc2822.md): Format a zoned ISO 8601 datetime string as an RFC 5322 (RFC 2822) date-time
- [formatRfc3339](https://gmt-dox.northguild.workers.dev/reference/zoned/format/formatRfc3339.md): Format a zoned ISO 8601 datetime string as strict RFC 3339 — the ISO 8601
- [formatTimeZoneName](https://gmt-dox.northguild.workers.dev/reference/zoned/format/formatTimeZoneName.md): Return the localized display name for an IANA timeZone.
- [FormatTimeZoneNameOptions](https://gmt-dox.northguild.workers.dev/reference/zoned/format/FormatTimeZoneNameOptions.md): The FormatTimeZoneNameOptions type.
- [formatZonedDateTime](https://gmt-dox.northguild.workers.dev/reference/zoned/format/formatZonedDateTime.md): Format a zoned ISO 8601 datetime string using the Intl.DateTimeFormat implementation.
- [formatZonedRange](https://gmt-dox.northguild.workers.dev/reference/zoned/format/formatZonedRange.md): Format a zoned datetime range using the Temporal Intl.DateTimeFormat formatRange API.
- [formatZonedToParts](https://gmt-dox.northguild.workers.dev/reference/zoned/format/formatZonedToParts.md): Return the locale-formatted parts of a ZonedDateTime.
- [getDstTransitions](https://gmt-dox.northguild.workers.dev/reference/zoned/get/getDstTransitions.md): List every DST transition instant for an IANA timezone within a given year.
- [getHoursInZonedDay](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/getHoursInZonedDay.md): Return the number of hours in the calendar day a zoned datetime falls on.
- [getLocaleZonedDayOfWeek](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/getLocaleZonedDayOfWeek.md): Return the locale-relative day-of-week index for a zoned `value`.
- [getLocaleZonedEndOfWeek](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/getLocaleZonedEndOfWeek.md): Return the end of the week containing `value`, using `locale`'s first
- [getLocaleZonedStartOfWeek](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/getLocaleZonedStartOfWeek.md): Return the start of the week containing `value`, using `locale`'s
- [getQuarterForZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/getQuarterForZoned.md): Return the quarter of the year (1-4) for a given zoned ISO datetime.
- [getSystemTimeZone](https://gmt-dox.northguild.workers.dev/reference/zoned/get/getSystemTimeZone.md): Return the runtime system timeZone name (for example "America/New_York").
- [getTimeZoneOffset](https://gmt-dox.northguild.workers.dev/reference/zoned/get/getTimeZoneOffset.md): Return an IANA timeZone's UTC offset at a given instant.
- [getTimeZones](https://gmt-dox.northguild.workers.dev/reference/zoned/get/getTimeZones.md): Return the array of all available IANA timezone identifiers.
- [getZonedDay](https://gmt-dox.northguild.workers.dev/reference/zoned/get/getZonedDay.md): Return the current day of month for the specified IANA timeZone.
- [getZonedDayOfWeek](https://gmt-dox.northguild.workers.dev/reference/zoned/get/getZonedDayOfWeek.md): Return the current day of week for the specified IANA timeZone.
- [getZonedHour](https://gmt-dox.northguild.workers.dev/reference/zoned/get/getZonedHour.md): Return the current hour for the specified IANA timeZone.
- [getZonedMicrosecond](https://gmt-dox.northguild.workers.dev/reference/zoned/get/getZonedMicrosecond.md): Return the current microsecond for the specified IANA timeZone.
- [getZonedMillisecond](https://gmt-dox.northguild.workers.dev/reference/zoned/get/getZonedMillisecond.md): Return the current millisecond for the specified IANA timeZone.
- [getZonedMinute](https://gmt-dox.northguild.workers.dev/reference/zoned/get/getZonedMinute.md): Return the current minute for the specified IANA timeZone.
- [getZonedMonth](https://gmt-dox.northguild.workers.dev/reference/zoned/get/getZonedMonth.md): Return the current month for the specified IANA timeZone.
- [getZonedNanosecond](https://gmt-dox.northguild.workers.dev/reference/zoned/get/getZonedNanosecond.md): Return the current nanosecond for the specified IANA timeZone.
- [getZonedNow](https://gmt-dox.northguild.workers.dev/reference/zoned/get/getZonedNow.md): Return the current zoned datetime for the specified IANA timeZone.
- [getZonedNowUnit](https://gmt-dox.northguild.workers.dev/reference/zoned/get/getZonedNowUnit.md): Return the requested current unit value for the specified IANA timeZone.
- [getZonedOffset](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/getZonedOffset.md): Extract the UTC offset from an ISO 8601 zoned datetime string.
- [getZonedOffsetAs](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/getZonedOffsetAs.md): Read a zoned value's UTC offset as a number, in the given unit.
- [getZonedSecond](https://gmt-dox.northguild.workers.dev/reference/zoned/get/getZonedSecond.md): Return the current second for the specified IANA timeZone.
- [getZonedToday](https://gmt-dox.northguild.workers.dev/reference/zoned/get/getZonedToday.md): Return today's date in the given IANA timeZone as an ISO date string.
- [getZonedWeekOfYear](https://gmt-dox.northguild.workers.dev/reference/zoned/get/getZonedWeekOfYear.md): Return the current week of year for the specified IANA timeZone.
- [getZonedYear](https://gmt-dox.northguild.workers.dev/reference/zoned/get/getZonedYear.md): Return the current year for the specified IANA timeZone.
- [hasDaylightSaving](https://gmt-dox.northguild.workers.dev/reference/zoned/validate/hasDaylightSaving.md): Check whether an IANA timeZone identifier observes daylight saving time.
- [intervalAbutsZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/intervalAbutsZoned.md): Return true when two zoned intervals are exactly adjacent — one's end equals the other's
- [intervalContainsZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/intervalContainsZoned.md): Return true when `pointOrStart` falls within the interval `[intervalStart, intervalEnd]`
- [intervalCountZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/intervalCountZoned.md): Count how many `unit` boundaries a zoned interval crosses.
- [intervalDifferenceZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/intervalDifferenceZoned.md): Return the portion(s) of interval A not covered by interval B.
- [intervalDivideEquallyZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/intervalDivideEquallyZoned.md): Split a zoned interval into `n` equal-length sub-intervals.
- [intervalEngulfsZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/intervalEngulfsZoned.md): Return true when interval B is fully contained within interval A — every instant of B
- [intervalFromDurationZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/intervalFromDurationZoned.md): Construct a zoned interval from a single point plus an ISO 8601 duration, anchored at either end.
- [intervalIntersectionZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/intervalIntersectionZoned.md): Return the overlapping span of two zoned intervals, or null when they do not overlap.
- [intervalLengthZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/intervalLengthZoned.md): Return the exact length of a zoned interval in `unit`, as a real (possibly fractional) number.
- [intervalOverlappingDaysZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/intervalOverlappingDaysZoned.md): Return how many distinct calendar dates two zoned intervals share, counted in the
- [intervalsOverlapZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/intervalsOverlapZoned.md): Return true when intervals `[aStart, aEnd]` and `[bStart, bEnd]` share at least one instant.
- [intervalSplitAtZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/intervalSplitAtZoned.md): Split a zoned interval at arbitrary `points`, producing consecutive sub-intervals.
- [intervalUnionZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/intervalUnionZoned.md): Return the combined span of two zoned intervals, or null when they are disjoint.
- [intervalXorAllZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/intervalXorAllZoned.md): Return the symmetric difference across a list of zoned intervals — the set of instants
- [intervalXorZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/intervalXorZoned.md): Return the symmetric difference of two zoned intervals — time covered by exactly one interval.
- [isAfterZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/compare/isAfterZoned.md): Return whether `value1` represents an instant strictly after `value2`.
- [isBeforeZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/compare/isBeforeZoned.md): Return whether `value1` represents an instant strictly before `value2`.
- [isBetweenZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/compare/isBetweenZoned.md): Return true when `zoned` is between `start` and `end` (inclusive by default).
- [isInDaylightSaving](https://gmt-dox.northguild.workers.dev/reference/zoned/compare/isInDaylightSaving.md): Check whether a zoned value's instant falls within daylight saving time.
- [isValidCalendarZonedDateTime](https://gmt-dox.northguild.workers.dev/reference/zoned/validate/isValidCalendarZonedDateTime.md): Return true if `value` is a valid GMT ZonedDateTime string: a bare ISO zoned datetime
- [isValidCalendarZonedInterval](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/isValidCalendarZonedInterval.md): Return true if `start` and `end` form a valid GMT zoned interval — both parseable as bare ISO
- [isValidTimeZone](https://gmt-dox.northguild.workers.dev/reference/zoned/validate/isValidTimeZone.md): Validate whether a string is a valid IANA timeZone identifier.
- [isValidZonedDateTime](https://gmt-dox.northguild.workers.dev/reference/zoned/validate/isValidZonedDateTime.md): Validate whether a string is a valid ISO 8601 zoned datetime string.
- [isValidZonedInterval](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/isValidZonedInterval.md): Return true if `start` and `end` form a valid zoned interval — both parseable as
- [isValidZonedNowUnit](https://gmt-dox.northguild.workers.dev/reference/zoned/get/isValidZonedNowUnit.md)
- [isValidZonedOffsetUnit](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/isValidZonedOffsetUnit.md)
- [isValidZonedRange](https://gmt-dox.northguild.workers.dev/reference/zoned/validate/isValidZonedRange.md): Return true if `value1` and `value2` form a valid zoned range — both parseable as
- [isValidZonedUnit](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/isValidZonedUnit.md)
- [isZonedBusinessDay](https://gmt-dox.northguild.workers.dev/reference/zoned/compare/isZonedBusinessDay.md): Return true when `value` falls on a Monday–Friday ISO business day in the given timezone.
- [isZonedFuture](https://gmt-dox.northguild.workers.dev/reference/zoned/compare/isZonedFuture.md): Return true when `value` represents an instant strictly after now.
- [isZonedPast](https://gmt-dox.northguild.workers.dev/reference/zoned/compare/isZonedPast.md): Return true when `value` represents an instant strictly before now.
- [isZonedRelativeDay](https://gmt-dox.northguild.workers.dev/reference/zoned/compare/isZonedRelativeDay.md): Return true when `value`'s local calendar day falls `offsetDays` days from
- [isZonedThisUnit](https://gmt-dox.northguild.workers.dev/reference/zoned/compare/isZonedThisUnit.md): Return true when `value`'s local calendar day falls in the same `unit` as
- [isZonedWeekend](https://gmt-dox.northguild.workers.dev/reference/zoned/compare/isZonedWeekend.md): Return true when `value`'s local calendar day falls on a weekend for `locale`.
- [mapZonedDatesInRange](https://gmt-dox.northguild.workers.dev/reference/zoned/map/mapZonedDatesInRange.md): Return an array of plain ISO date strings covering the inclusive date range between two zoned datetimes.
- [mapZonedHoursInDay](https://gmt-dox.northguild.workers.dev/reference/zoned/map/mapZonedHoursInDay.md): Return an array of zoned datetime strings representing each hour boundary for the 24-hour window starting at midnight of the anchor's local day.
- [maxZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/maxZoned.md): Return the latest (maximum) of the given ZonedDateTime values.
- [mergeIntervalsZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/mergeIntervalsZoned.md): Collapse a list of zoned intervals into the minimum set of non-overlapping intervals.
- [minZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/minZoned.md): Return the earliest (minimum) of the given ZonedDateTime values.
- [parseDateFromZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/parseDateFromZoned.md): Extract the plain date portion from an ISO 8601 zoned datetime string.
- [parseDateTimeFromZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/parseDateTimeFromZoned.md)
- [parseDayFromZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/parseDayFromZoned.md): Return the day (1-31) from a zoned datetime string.
- [parseDayOfWeekFromZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/parseDayOfWeekFromZoned.md): Return the day of the week (1-7, Monday-Sunday) from a zoned datetime string.
- [parseHourFromZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/parseHourFromZoned.md): Return the hour (0-23) from a zoned datetime string.
- [parseMicrosecondFromZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/parseMicrosecondFromZoned.md): Return the microsecond (0-999) from a zoned datetime string.
- [parseMillisecondFromZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/parseMillisecondFromZoned.md): Return the millisecond (0-999) from a zoned datetime string.
- [parseMinuteFromZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/parseMinuteFromZoned.md): Return the minute (0-59) from a zoned datetime string.
- [parseMonthFromZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/parseMonthFromZoned.md): Return the month (1-12) from a zoned datetime string.
- [parseNanosecondFromZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/parseNanosecondFromZoned.md): Return the nanosecond (0-999) from a zoned datetime string.
- [parseRfc2822](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/parseRfc2822.md): Parse an RFC 5322 (RFC 2822) date-time string — the fixed grammar email
- [parseRfc3339](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/parseRfc3339.md): Parse a strict RFC 3339 datetime string into a zoned ISO 8601 datetime
- [parseSecondFromZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/parseSecondFromZoned.md): Return the second (0-59) from a zoned datetime string.
- [parseTimeFromZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/parseTimeFromZoned.md): Extract the plain time portion from an ISO 8601 zoned datetime string.
- [parseTimeZoneFromZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/parseTimeZoneFromZoned.md): Extract the IANA timeZone identifier from an ISO 8601 zoned datetime string.
- [parseUnitFromZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/parseUnitFromZoned.md): Return the requested unit value from an ISO 8601 zoned datetime string.
- [parseWeekFromZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/parseWeekFromZoned.md): Return the week of the year (1-53) for a given ISO 8601 zoned datetime string.
- [parseYearFromZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/parseYearFromZoned.md): Return the year for a given ISO 8601 zoned datetime string.
- [RelativeUnit](https://gmt-dox.northguild.workers.dev/reference/zoned/format/RelativeUnit.md): Intl.RelativeTimeFormatUnit includes "quarter" which Temporal doesn't support.
- [roundZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/roundZoned.md): Round an ISO 8601 zoned datetime string to the specified unit.
- [setZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/setZoned.md): Return a zoned ISO 8601 datetime string with the given `fields` set on `value`.
- [sortZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/sortZoned.md): Sort an array of ZonedDateTime values in ascending or descending order.
- [splitIntervalByUnitZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/interval/splitIntervalByUnitZoned.md): Split a zoned interval into sub-intervals of `amount × unit`.
- [startOfQuarterForZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/startOfQuarterForZoned.md): Return the start of the quarter for a given zoned ISO datetime.
- [startOfZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/startOfZoned.md): Return the start of the specified date-time `unit` for a given zoned ISO 8601 datetime string.
- [subtractZoned](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/subtractZoned.md): Subtract a temporal amount from a zoned ISO 8601 datetime string and return a zoned ISO 8601 string.
- [subtractZonedBusinessDays](https://gmt-dox.northguild.workers.dev/reference/zoned/calculate/subtractZonedBusinessDays.md): Return a zoned ISO 8601 datetime string with `amount` business days subtracted from `value`.
- [TimeZoneNameStyle](https://gmt-dox.northguild.workers.dev/reference/zoned/format/TimeZoneNameStyle.md): The TimeZoneNameStyle type.
- [ZonedNowUnit](https://gmt-dox.northguild.workers.dev/reference/zoned/get/ZonedNowUnit.md): The ZonedNowUnit type.
- [ZonedOffsetUnit](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/ZonedOffsetUnit.md): The ZonedOffsetUnit type.
- [ZonedParseUnit](https://gmt-dox.northguild.workers.dev/reference/zoned/parse/ZonedParseUnit.md): The ZonedParseUnit type.

## Guides

- [Application Integration](https://gmt-dox.northguild.workers.dev/guides/integration/app-integration.md): Integrate gmt with routers, query caches, table libraries, and state management — cache-key hygiene and canonical representations at boundaries.
- [Calendar Systems](https://gmt-dox.northguild.workers.dev/guides/core-date-operations/calendar-systems.md): Express a date in a non-Gregorian calendar system (Hebrew, Islamic, Japanese, Buddhist, and more) with calendar-native arithmetic.
- [Comparisons](https://gmt-dox.northguild.workers.dev/guides/core-date-operations/comparisons.md): Compare dates for ordering, check equality at a given unit, and test for weekends, business days, and now-relative predicates.
- [Concepts](https://gmt-dox.northguild.workers.dev/guides/concepts/index.md): Foundational ideas — the two families of types and how DST disambiguation works.
- [Containment and Overlap](https://gmt-dox.northguild.workers.dev/guides/intervals/containment-and-overlap.md): Test whether a point or interval is contained, whether two intervals overlap, and compute their intersection.
- [Conversion](https://gmt-dox.northguild.workers.dev/guides/conversion/index.md): Between plain, zoned, unix, and UTC representations, and non-Gregorian calendar systems.
- [Converting Between Types](https://gmt-dox.northguild.workers.dev/guides/conversion/converting-types.md): Convert between plain, zoned, unix, and UTC representations, and express dates in non-Gregorian calendar systems.
- [Core Date Operations](https://gmt-dox.northguild.workers.dev/guides/core-date-operations/index.md): Getting the current time, arithmetic, comparison, durations, parsing, formatting, validation, and calendar systems.
- [DST Disambiguation](https://gmt-dox.northguild.workers.dev/guides/concepts/dst-disambiguation.md): >
- [Durations](https://gmt-dox.northguild.workers.dev/guides/core-date-operations/durations.md): Parse, validate, combine, rebalance, and format ISO 8601 duration strings — distinct from date arithmetic.
- [Formatting](https://gmt-dox.northguild.workers.dev/guides/core-date-operations/formatting.md): Format date/time values for display with locale support, locale-ordered parts, relative labels, calendar-day labels, and fixed machine formats.
- [Getting the Current Date and Time](https://gmt-dox.northguild.workers.dev/guides/core-date-operations/get-current.md): Read the current date, time, datetime, or timestamp as ISO strings — plain, zoned, UTC, and Unix.
- [Integration](https://gmt-dox.northguild.workers.dev/guides/integration/index.md): Integrate gmt with routers, query caches, table libraries, state management, and lint config.
- [Interval Basics](https://gmt-dox.northguild.workers.dev/guides/intervals/interval-basics.md): Validate intervals and ranges, construct them from a point plus a duration, and understand the two API shapes.
- [Intervals](https://gmt-dox.northguild.workers.dev/guides/core-date-operations/intervals/index.md): Range math — containment, overlap, set operations, splitting, and counting.
- [Lint Package Selection](https://gmt-dox.northguild.workers.dev/guides/integration/linting.md): Choose the right @northguild lint package (ESLint, Biome, Oxlint) and bridge lint-only setups to the gmt runtime.
- [Parsing](https://gmt-dox.northguild.workers.dev/guides/core-date-operations/parsing.md): Extract components from ISO strings and decode fixed interchange grammars (email, HTTP, SQL, RFC 3339) into GMT's own ISO strings.
- [Plain Arithmetic](https://gmt-dox.northguild.workers.dev/guides/core-date-operations/plain-arithmetic.md): Add, subtract, and diff dates and datetimes in the timezone-free plain namespace — including business days, overflow control, and rounding.
- [Plain vs Zoned](https://gmt-dox.northguild.workers.dev/guides/concepts/plain-vs-zoned.md): The two families of Temporal types in GMT — timezone-free and timezone-aware — and why they never mix.
- [Relative Time](https://gmt-dox.northguild.workers.dev/guides/core-date-operations/relative-time.md): Produce human-friendly relative strings ("yesterday", "in 2 hours") across plain, zoned, unix, and UTC values — with shared options and DST-safe zoned arithmetic.
- [Set Operations](https://gmt-dox.northguild.workers.dev/guides/intervals/set-operations.md): Union, difference, xor, merge, and symmetric-difference over intervals — returning spans or arrays of spans.
- [Splitting and Counting](https://gmt-dox.northguild.workers.dev/guides/intervals/splitting-and-counting.md): Split intervals by duration unit or into equal parts, count calendar-unit boundaries crossed, and measure exact fractional length.
- [Validation](https://gmt-dox.northguild.workers.dev/guides/core-date-operations/validation.md): Validate date/time strings, timezone identifiers, intervals, and ranges before processing — sentinels instead of thrown errors.
- [Zoned Operations](https://gmt-dox.northguild.workers.dev/guides/zoned-date-operations/zoned-operations.md): Timezone-aware arithmetic, boundaries, DST disambiguation, and offset control — scheduling across timezones correctly.

## Scenarios

- [Monthly Billing Without Drift](https://gmt-dox.northguild.workers.dev/scenarios/monthly-billing.md): Charge on the same calendar date every month, not a fixed number of days.
- [Recurring Meeting Across DST](https://gmt-dox.northguild.workers.dev/scenarios/recurring-meeting-dst.md): Schedule a meeting that repeats weekly across a daylight saving time boundary.
- [Storing a Birthday](https://gmt-dox.northguild.workers.dev/scenarios/storing-birthday.md): Store a birthday so it stays correct across timezones and years.

## Mistakes

- [Date Arithmetic](https://gmt-dox.northguild.workers.dev/mistakes/calculate-dates.md): Common mistakes when performing date arithmetic with GMT.
- [Date Comparison](https://gmt-dox.northguild.workers.dev/mistakes/compare-dates.md): Common mistakes when comparing dates with GMT.
- [Date Validation](https://gmt-dox.northguild.workers.dev/mistakes/validate-dates.md): Common mistakes when validating dates with GMT.
- [Duration](https://gmt-dox.northguild.workers.dev/mistakes/durations.md): Common mistakes when working with durations in GMT.
- [Formatting Date and Time](https://gmt-dox.northguild.workers.dev/mistakes/format-date-time.md): Common mistakes when formatting date and time values with GMT.
- [Formatting Relative Time](https://gmt-dox.northguild.workers.dev/mistakes/format-relative-time.md): Common mistakes when formatting relative time descriptions with GMT.
- [Getting the Current Time](https://gmt-dox.northguild.workers.dev/mistakes/get-current.md): Common mistakes when getting the current time with GMT.
- [Interval Operations](https://gmt-dox.northguild.workers.dev/mistakes/interval-ops.md): Common mistakes when working with date and time intervals in GMT.
- [Parsing Date and Time](https://gmt-dox.northguild.workers.dev/mistakes/parse-date-time.md): Common mistakes when parsing date and time values with GMT.
- [Type Conversion](https://gmt-dox.northguild.workers.dev/mistakes/convert-types.md): Common mistakes when converting between date/time types with GMT.
- [Zoned Date Operations](https://gmt-dox.northguild.workers.dev/mistakes/zoned-date-ops.md): Common mistakes when working with zoned dates and timezones in GMT.