Sync calendar annotation format with the IETF draft

IETF is moving forward with [n-kk=vvvvv] (n=namespace, k=key, v=value)
rather than [n-kk-vvvvv]. By definition, Temporal uses the format that is
being standardized within IETF.

Update the note in the spec text as well to remove the text saying that
the format is tentative. This is the format that IETF is moving forward
with.

Closes: #1409
Closes: #1412

docs/ambiguity.md

@@ -83,7 +83,7 @@ zdt = instant.toZonedDateTime('Asia/Tokyo', 'iso8601').toLocaleString('ja-jp', f
   // this is identical to the result of toZonedDateTime() above
 
 zdt = instant.toZonedDateTime('Asia/Tokyo', 'japanese');
-  // => 2019-09-03T17:34:05+09:00[Asia/Tokyo][u-ca-japanese]
+  // => 2019-09-03T17:34:05+09:00[Asia/Tokyo][u-ca=japanese]
 zdt.toLocaleString('en-us', { ...formatOptions, calendar: zdt.calendar });
   // => "Sep 3, 1 Reiwa, 5:34:05 PM"
 zdt.year;

docs/calendar.md

@@ -117,7 +117,7 @@ For a list of calendar identifiers, see the documentation for [Intl.DateTimeForm
 If `calendarIdentifier` is not a built-in calendar, then a `RangeError` is thrown.
 
 Use this constructor directly if you have a string that is known to be a correct built-in calendar identifier.
-If you have an ISO 8601 date-time string with a `[u-ca-identifier]` annotation, then `Temporal.Calendar.from()` is more convenient than parsing the identifier out of the string, and also the only way to parse strings annotated with a non-built-in calendar.
+If you have an ISO 8601 date-time string with a `[u-ca=identifier]` annotation, then `Temporal.Calendar.from()` is more convenient than parsing the identifier out of the string, and also the only way to parse strings annotated with a non-built-in calendar.
 
 Example usage:
 
@@ -146,7 +146,7 @@ Any other value is converted to a string, which is expected to be either:
 - a string that is accepted by `new Temporal.Calendar()`; or
 - a string in the ISO 8601 format.
 
-Note that the ISO 8601 string can be extended with a `[u-ca-identifier]` annotation in square brackets appended to it.
+Note that the ISO 8601 string can be extended with a `[u-ca=identifier]` annotation in square brackets appended to it.
 Without such an annotation, the calendar is taken to be `iso8601`.
 
 This function is often more convenient to use than `new Temporal.Calendar()` because it handles a wider range of input.
@@ -160,7 +160,7 @@ cal = Temporal.Calendar.from('gregory');
 
 // ISO 8601 string with or without calendar annotation
 cal = Temporal.Calendar.from('2020-01-13T16:31:00.065858086');
-cal = Temporal.Calendar.from('2020-01-13T16:31:00.065858086-08:00[America/Vancouver][u-ca-iso8601]');
+cal = Temporal.Calendar.from('2020-01-13T16:31:00.065858086-08:00[America/Vancouver][u-ca=iso8601]');
 
 // Existing calendar object
 cal2 = Temporal.Calendar.from(cal);
@@ -169,7 +169,7 @@ cal2 = Temporal.Calendar.from(cal);
 cal = Temporal.Calendar.from({ id: 'mycalendar' });
 
 /*⚠️*/ cal = Temporal.Calendar.from('discordian'); // not a built-in calendar, throws
-/*⚠️*/ cal = Temporal.Calendar.from('[u-ca-iso8601]'); // lone annotation not a valid ISO 8601 string
+/*⚠️*/ cal = Temporal.Calendar.from('[u-ca=iso8601]'); // lone annotation not a valid ISO 8601 string
 ```
 
 ## Properties
@@ -273,7 +273,7 @@ date.year; // => 5779
 date.month; // => 6
 date.monthCode; // => "M05L"
 date.day; // => 18
-date.toString(); // => 2019-02-23[u-ca-hebrew]
+date.toString(); // => 2019-02-23[u-ca=hebrew]
 date.toLocaleString('en-US', { calendar: 'hebrew' }); // => "18 Adar I 5779"
 
 // same result, but calling the method directly and using month index instead of month code:
@@ -320,7 +320,7 @@ date = Temporal.PlainDate.from('2020-05-29')
 date.year; // => 1441
 date.month; // => 11
 date.day; // => 7
-date.toString(); // => 2020-06-28[u-ca-islamic]
+date.toString(); // => 2020-06-28[u-ca=islamic]
 
 // same result, but calling the method directly:
 date = Temporal.Calendar.from('islamic').dateAdd(
@@ -332,7 +332,7 @@ date = Temporal.Calendar.from('islamic').dateAdd(
 date.year; // => 1441
 date.month; // => 11
 date.day; // => 7
-date.toString(); // => 2020-06-28[u-ca-islamic]
+date.toString(); // => 2020-06-28[u-ca=islamic]
 ```
 
 ### calendar.**dateUntil**(_one_: Temporal.PlainDate | object | string, _two_: Temporal.PlainDate | object | string, _options_: object) : Temporal.Duration
@@ -445,7 +445,7 @@ This method overrides `Object.prototype.toString()` and provides the calendar's
 Example usage:
 
 ```javascript
-Temporal.PlainDate.from('2020-05-29[u-ca-gregory]').calendar.toString(); // => gregory
+Temporal.PlainDate.from('2020-05-29[u-ca=gregory]').calendar.toString(); // => gregory
 ```
 
 ### calendar.**toJSON**() : string

docs/instant.md

@@ -274,13 +274,13 @@ Example usage:
 epoch = Temporal.Instant.fromEpochSeconds(0);
 timeZone = Temporal.TimeZone.from('America/New_York');
 epoch.toZonedDateTime({ timeZone, calendar: 'gregory' });
-  // => 1969-12-31T19:00-05:00[America/New_York][u-ca-gregory]
+  // => 1969-12-31T19:00-05:00[America/New_York][u-ca=gregory]
 
 // What time was the Unix epoch in Tokyo in the Japanese calendar?
 timeZone = Temporal.TimeZone.from('Asia/Tokyo');
 calendar = Temporal.Calendar.from('japanese');
 zdt = epoch.toZonedDateTime({ timeZone, calendar });
-  // => 1970-01-01T09:00+09:00[Asia/Tokyo][u-ca-japanese]
+  // => 1970-01-01T09:00+09:00[Asia/Tokyo][u-ca=japanese]
 console.log(zdt.year, zdt.era);
   // => 45 showa
 ```

docs/iso-string-ext.md

@@ -55,7 +55,7 @@ _Calendar-specific dates are expressed as their equivalent date in the ISO calen
 For example, when parsed, the following string would represent the date **28 Iyar 5780** in the Hebrew calendar:
 
 ```
-2020-05-22[u-ca-hebrew]
+2020-05-22[u-ca=hebrew]
 ```
 
 The syntax of the calendar suffix is currently being proposed for standardization with the CalConnect and IETF Calsify standards bodies.
@@ -86,7 +86,7 @@ The list of calendar identifiers currently supported by CLDR is:
 Example of a maximal length string containing both an IANA time zone name and a calendar system:
 
 ```
-2020-05-22T07:19:35.356-04:00[America/Indiana/Indianapolis][u-ca-islamic-umalqura]
+2020-05-22T07:19:35.356-04:00[America/Indiana/Indianapolis][u-ca=islamic-umalqura]
 ```
 
 ### Calendar-dependent YearMonth and MonthDay

docs/plaindate.md

@@ -99,7 +99,7 @@ date = Temporal.PlainDate.from(Temporal.PlainDateTime.from('2006-08-24T15:43:27'
   // => same as above; Temporal.PlainDateTime has year, month, and day properties
 
 calendar = Temporal.Calendar.from('islamic');
-date = Temporal.PlainDate.from({ year: 1427, month; 8, day: 1, calendar }); // => 2006-08-24[u-ca-islamic]
+date = Temporal.PlainDate.from({ year: 1427, month; 8, day: 1, calendar }); // => 2006-08-24[u-ca=islamic]
 date = Temporal.PlainDate.from({ year: 1427, month: 8, day: 1, calendar: 'islamic' });
   // => same as above
 
@@ -185,7 +185,7 @@ date.month;     // => 8
 date.monthCode; // => "M08"
 date.day;       // => 24
 
-date = Temporal.PlainDate.from('2019-02-23[u-ca-hebrew]');
+date = Temporal.PlainDate.from('2019-02-23[u-ca=hebrew]');
 date.year;      // => 5779
 date.month;     // => 6
 date.monthCode; // => "M05L"
@@ -207,7 +207,7 @@ As inputs to `from` or `with`, `era` and `eraYear` can be used instead of `year`
 Unlike `year`, `eraYear` may decrease as time proceeds because some eras (like the BCE era in the Gregorian calendar) count years backwards.
 
 ```javascript
-date = Temporal.PlainDate.from('-000015-01-01[u-ca-gregory]');
+date = Temporal.PlainDate.from('-000015-01-01[u-ca=gregory]');
 date.era;
 // => "bce"
 date.eraYear;
@@ -384,7 +384,7 @@ This method is the same as `date.with({ calendar })`, but may be more efficient.
 Usage example:
 
 ```javascript
-date = Temporal.PlainDate.from('2006-08-24[u-ca-japanese]');
+date = Temporal.PlainDate.from('2006-08-24[u-ca=japanese]');
 date.withCalendar('iso8601'); // => 2006-08-24
 ```
 

docs/plaindatetime.md

@@ -145,7 +145,7 @@ dt = Temporal.PlainDateTime.from(Temporal.PlainDate.from('1995-12-07T03:24:30'))
 
 calendar = Temporal.Calendar.from('hebrew');
 dt = Temporal.PlainDateTime.from({ year: 5756, month: 3, day: 14, hour: 3, minute: 24, second: 30, calendar });
-  // => 1995-12-07T03:24:30[u-ca-hebrew]
+  // => 1995-12-07T03:24:30[u-ca=hebrew]
 dt = Temporal.PlainDateTime.from({ year: 5756, month: 3, day: 14, hour: 3, minute: 24, second: 30, calendar: 'hebrew' });
   // => same as above
 
@@ -277,7 +277,7 @@ dt.millisecond; // => 0
 dt.microsecond; // => 3
 dt.nanosecond;  // => 500
 
-dt = Temporal.PlainDate.from('2019-02-23T03:24:30.000003500[u-ca-hebrew]');
+dt = Temporal.PlainDate.from('2019-02-23T03:24:30.000003500[u-ca=hebrew]');
 dt.year;        // => 5779
 dt.month;       // => 6
 dt.monthCode;   // => "M05L"
@@ -305,7 +305,7 @@ As inputs to `from` or `with`, `era` and `eraYear` can be used instead of `year`
 Unlike `year`, `eraYear` may decrease as time proceeds because some eras (like the BCE era in the Gregorian calendar) count years backwards.
 
 ```javascript
-date = Temporal.PlainDateTime.from('-000015-01-01T12:30[u-ca-gregory]');
+date = Temporal.PlainDateTime.from('-000015-01-01T12:30[u-ca=gregory]');
 date.era;
 // => "bce"
 date.eraYear;
@@ -536,9 +536,9 @@ dt.withPlainDate('2018-09-15'); // => 2018-09-15T03:24:30
 dt.add({ hours: 12 }).withPlainDate('2000-06-01'); // => 2000-06-01T15:24:30
 
 // result contains a non-ISO calendar if present in the input
-dt.withCalendar('japanese').withPlainDate('2008-09-06'); // => 2008-09-06T03:24:30[u-ca-japanese]
-dt.withPlainDate('2017-09-06[u-ca-japanese]'); // => 2017-09-06T03:24:30[u-ca-japanese]
-dt.withCalendar('japanese').withPlainDate('2017-09-06[u-ca-hebrew]'); // => RangeError (calendar conflict)
+dt.withCalendar('japanese').withPlainDate('2008-09-06'); // => 2008-09-06T03:24:30[u-ca=japanese]
+dt.withPlainDate('2017-09-06[u-ca=japanese]'); // => 2017-09-06T03:24:30[u-ca=japanese]
+dt.withCalendar('japanese').withPlainDate('2017-09-06[u-ca=hebrew]'); // => RangeError (calendar conflict)
 ```
 
 ### datetime.**withCalendar**(_calendar_: object | string) : Temporal.PlainDateTime
@@ -554,7 +554,7 @@ This method is the same as `datetime.with({ calendar })`, but may be more effici
 Usage example:
 
 ```javascript
-dt = Temporal.PlainDateTime.from('1995-12-07T03:24:30.000003500[u-ca-japanese]');
+dt = Temporal.PlainDateTime.from('1995-12-07T03:24:30.000003500[u-ca=japanese]');
 dt.withCalendar('iso8601'); // => 1995-12-07T03:24:30.000003500
 ```
 

docs/plainmonthday.md

@@ -115,12 +115,12 @@ md = Temporal.PlainMonthDay.from({ month: 2, day: 29, year: 2001 }, { overflow:
 
 // non-ISO calendars
 md = Temporal.PlainMonthDay.from({ monthCode: 'M05L', day: 15, calendar: 'hebrew' });
-// => 2019-02-20[u-ca-hebrew]
+// => 2019-02-20[u-ca=hebrew]
 md = Temporal.PlainMonthDay.from({ month: 6, day: 15, year: 5779, calendar: 'hebrew' });
-// => 2019-02-20[u-ca-hebrew]
+// => 2019-02-20[u-ca=hebrew]
 md = Temporal.PlainMonthDay.from({ month: 6, day: 15, calendar: 'hebrew' });
 // => throws (either year or monthCode is required)
-md = Temporal.PlainMonthDay.from('2019-02-20[u-ca-hebrew]');
+md = Temporal.PlainMonthDay.from('2019-02-20[u-ca=hebrew]');
 md.monthCode; // => "M05L"
 md.day; // => 15
 md.month; // undefined (month property is not present in this type; use monthCode instead)
@@ -151,7 +151,7 @@ md.monthCode; // => "M08"
 md.day; // => 24
 md.month; // undefined (no `month` property; use `monthCode` instead)
 
-md = Temporal.PlainMonthDay.from('2019-02-20[u-ca-hebrew]');
+md = Temporal.PlainMonthDay.from('2019-02-20[u-ca=hebrew]');
 md.monthCode; // => "M05L"
 md.day; // => 15
 md.month; // undefined (no `month` property; use `monthCode` instead)

docs/plainyearmonth.md

@@ -181,7 +181,7 @@ ym.year; // => 2019
 ym.month; // => 6
 ym.monthCode; // => "M06"
 
-ym = Temporal.PlainYearMonth.from('2019-02-23[u-ca-hebrew]');
+ym = Temporal.PlainYearMonth.from('2019-02-23[u-ca=hebrew]');
 ym.year; // => 5779
 ym.month; // => 6
 ym.monthCode; // => "M05L"
@@ -202,7 +202,7 @@ As inputs to `from` or `with`, `era` and `eraYear` can be used instead of `year`
 Unlike `year`, `eraYear` may decrease as time proceeds because some eras (like the BCE era in the Gregorian calendar) count years backwards.
 
 ```javascript
-ym = Temporal.PlainYearMonth.from('-000015-01-01[u-ca-gregory]');
+ym = Temporal.PlainYearMonth.from('-000015-01-01[u-ca=gregory]');
 ym.era;
 // => "bce"
 ym.eraYear;

docs/zoneddatetime.md

@@ -88,7 +88,7 @@ Any non-object value is converted to a string, which is expected to be an ISO 86
 For example:
 
 ```
-2020-08-05T20:06:13+09:00[Asia/Tokyo][u-ca-japanese]
+2020-08-05T20:06:13+09:00[Asia/Tokyo][u-ca=japanese]
 ```
 
 If the string isn't valid, then a `RangeError` will be thrown regardless of the value of `overflow`.
@@ -179,7 +179,7 @@ Example usage:
 <!-- prettier-ignore-start -->
 ```javascript
 zdt = Temporal.ZonedDateTime.from('1995-12-07T03:24:30+02:00[Africa/Cairo]');
-zdt = Temporal.ZonedDateTime.from('1995-12-07T03:24:30+02:00[Africa/Cairo][u-ca-islamic]');
+zdt = Temporal.ZonedDateTime.from('1995-12-07T03:24:30+02:00[Africa/Cairo][u-ca=islamic]');
 zdt = Temporal.ZonedDateTime.from('1995-12-07T03:24:30');  // RangeError; time zone ID required
 zdt = Temporal.ZonedDateTime.from('1995-12-07T01:24:30Z');  // RangeError; time zone ID required
 zdt = Temporal.ZonedDateTime.from('1995-12-07T03:24:30+02:00');  // RangeError; time zone ID required
@@ -337,7 +337,7 @@ dt.millisecond; // => 0
 dt.microsecond; // => 3
 dt.nanosecond;  // => 500
 
-dt = Temporal.ZonedDateTime.from('2019-02-23T03:24:30.000003500[Europe/Rome][u-ca-hebrew]');
+dt = Temporal.ZonedDateTime.from('2019-02-23T03:24:30.000003500[Europe/Rome][u-ca=hebrew]');
 dt.year;        // => 5779
 dt.month;       // => 6
 dt.monthCode;   // => "M05L"
@@ -466,7 +466,7 @@ As inputs to `from` or `with`, `era` and `eraYear` can be used instead of `year`
 Unlike `year`, `eraYear` may decrease as time proceeds because some eras (like the BCE era in the Gregorian calendar) count years backwards.
 
 ```javascript
-date = Temporal.ZonedDateTime.from('-000015-01-01T12:30[Europe/Rome][u-ca-gregory]');
+date = Temporal.ZonedDateTime.from('-000015-01-01T12:30[Europe/Rome][u-ca=gregory]');
 date.era;
 // => "bce"
 date.eraYear;
@@ -825,9 +825,9 @@ zdt.withPlainDate('2018-09-15'); // => 2018-09-15T03:24:30-07:00[America/Los_Ang
 zdt.add({ hours: 12 }).withPlainDate('2000-06-01'); // => 2000-06-01T15:24:30-07:00[America/Los_Angeles]
 
 // result contains a non-ISO calendar if present in the input
-zdt.withCalendar('japanese').withPlainDate('2008-09-06'); // => 2008-09-06T03:24:30-07:00[America/Los_Angeles][u-ca-japanese]
-zdt.withPlainDate('2017-09-06[u-ca-japanese]'); // => 2017-09-06T03:24:30-07:00[America/Los_Angeles][u-ca-japanese]
-zdt.withCalendar('japanese').withPlainDate('2017-09-06[u-ca-hebrew]'); // => RangeError (calendar conflict)
+zdt.withCalendar('japanese').withPlainDate('2008-09-06'); // => 2008-09-06T03:24:30-07:00[America/Los_Angeles][u-ca=japanese]
+zdt.withPlainDate('2017-09-06[u-ca=japanese]'); // => 2017-09-06T03:24:30-07:00[America/Los_Angeles][u-ca=japanese]
+zdt.withCalendar('japanese').withPlainDate('2017-09-06[u-ca=hebrew]'); // => RangeError (calendar conflict)
 ```
 
 ### zonedDateTime.**withTimeZone**(_timeZone_: object | string) : Temporal.ZonedDateTime
@@ -857,7 +857,7 @@ zdt.withTimeZone('Africa/Accra').toString(); // => "1995-12-06T18:24:30+00:00[Af
 Usage example:
 
 ```javascript
-zdt = Temporal.ZonedDateTime.from('1995-12-07T03:24:30.000003500+09:00[Asia/Tokyo][u-ca-japanese]');
+zdt = Temporal.ZonedDateTime.from('1995-12-07T03:24:30.000003500+09:00[Asia/Tokyo][u-ca=japanese]');
 `${zdt.era} ${zdt.year}`; // => "heisei 7"
 zdt.withCalendar('iso8601').year; // => 1995
 ```
@@ -1246,7 +1246,7 @@ zdt1.equals(zdt1); // => true
 Examples:
 
 - `2011-12-03T10:15:30+01:00[Europe/Paris]`
-- `2011-12-03T10:15:30+09:00[Asia/Tokyo][u-ca-japanese]`
+- `2011-12-03T10:15:30+09:00[Asia/Tokyo][u-ca=japanese]`
 
 This method overrides the `Object.prototype.toString()` method and provides a convenient, unambiguous string representation of `zonedDateTime`.
 The string is "round-trippable".
@@ -1273,7 +1273,7 @@ Example usage:
 zdt = Temporal.ZonedDateTime.from({ year: 2019, month: 12, day: 1, hour: 12, timeZone: 'Africa/Lagos' });
 zdt.toString(); // => 2019-12-01T12:00+01:00[Africa/Lagos]
 zdt.withCalendar('japanese');
-zdt.toString(); // => 2019-12-01T12:00+01:00[Africa/Lagos][u-ca-japanese]
+zdt.toString(); // => 2019-12-01T12:00+01:00[Africa/Lagos][u-ca=japanese]
 ```
 
 ### zonedDateTime.**toLocaleString**(_locales_?: string | array&lt;string&gt;, _options_?: object) : string

polyfill/lib/ecmascript.mjs

@@ -166,7 +166,7 @@ export const ES = ObjectAssign({}, ES2020, {
   FormatCalendarAnnotation: (id, showCalendar) => {
     if (showCalendar === 'never') return '';
     if (showCalendar === 'auto' && id === 'iso8601') return '';
-    return `[u-ca-${id}]`;
+    return `[u-ca=${id}]`;
   },
   ParseISODateTime: (isoString, { zoneRequired }) => {
     const regex = zoneRequired ? PARSE.instant : PARSE.datetime;

polyfill/lib/regex.mjs

@@ -1,30 +1,7 @@
-// Per specification,
-//   TZLeadingChar TZChar? TZChar? TZChar? TZChar? TZChar? TZChar? TZChar?
-//     TZChar? TZChar? TZChar? TZChar? TZChar? TZChar?
-//   but not one of `.` or `..` or
-//     CalChar `-` CalChar CalChar `-` CalendarNameComponent
-// In plain words, 1 to 14 letters, periods, underscores, or dashes, but not
-// starting with a dash, and not consisting only of one or two periods, and not
-// of the form (letter)-(2 letters)-(3 or more letters) which conflicts with
-// calComponent
-const tzComponentNotBCP47 = new RegExp(
-  [
-    '\\.\\.[-A-Za-z._]{1,12}',
-    '\\.[-A-Za-z_][-A-Za-z._]{0,12}',
-    '_[-A-Za-z._]{0,13}',
-    '[a-zA-Z](?:[A-Za-z._][-A-Za-z._]{0,12})?',
-    '[a-zA-Z]-(?:[-._][-A-Za-z._]{0,11})?',
-    '[a-zA-Z]-[a-zA-Z](?:[-._][-A-Za-z._]{0,10})?',
-    '[a-zA-Z]-[a-zA-Z][a-zA-Z](?:[A-Za-z._][-A-Za-z._]{0,9})?',
-    '[a-zA-Z]-[a-zA-Z][a-zA-Z]-(?:[-._][-A-Za-z._]{0,8})?',
-    '[a-zA-Z]-[a-zA-Z][a-zA-Z]-[a-zA-Z](?:[-._][-A-Za-z._]{0,7})?',
-    '[a-zA-Z]-[a-zA-Z][a-zA-Z]-[a-zA-Z][a-zA-Z](?:[-._][-A-Za-z._]{0,6})?'
-  ].join('|')
-);
 const tzComponent = /\.[-A-Za-z_]|\.\.[-A-Za-z._]{1,12}|\.[-A-Za-z_][-A-Za-z._]{0,12}|[A-Za-z_][-A-Za-z._]{0,13}/;
 const offsetNoCapture = /(?:[+\u2212-][0-2][0-9](?::?[0-5][0-9](?::?[0-5][0-9](?:[.,]\d{1,9})?)?)?)/;
 export const timeZoneID = new RegExp(
-  `(?:(?:${tzComponentNotBCP47.source})(?:\\/(?:${tzComponent.source}))*|Etc/GMT[-+]\\d{1,2}|${offsetNoCapture.source})`
+  `(?:(?:${tzComponent.source})(?:\\/(?:${tzComponent.source}))*|Etc/GMT[-+]\\d{1,2}|${offsetNoCapture.source})`
 );
 
 const calComponent = /[A-Za-z0-9]{3,8}/;
@@ -35,7 +12,7 @@ export const datesplit = new RegExp(`(${yearpart.source})(?:-(\\d{2})-(\\d{2})|(
 const timesplit = /(\d{2})(?::(\d{2})(?::(\d{2})(?:[.,](\d{1,9}))?)?|(\d{2})(?:(\d{2})(?:[.,](\d{1,9}))?)?)?/;
 export const offset = /([+\u2212-])([01][0-9]|2[0-3])(?::?([0-5][0-9])(?::?([0-5][0-9])(?:[.,](\d{1,9}))?)?)?/;
 const zonesplit = new RegExp(`(?:([zZ])|(?:${offset.source})?)(?:\\[(${timeZoneID.source})\\])?`);
-const calendar = new RegExp(`\\[u-ca-(${calendarID.source})\\]`);
+const calendar = new RegExp(`\\[u-ca=(${calendarID.source})\\]`);
 
 export const instant = new RegExp(
   `^${datesplit.source}(?:(?:T|\\s+)${timesplit.source})?${zonesplit.source}(?:${calendar.source})?$`,