共通の小構文 — Common microsyntaxes

2.3.4.1. 有符号~整数

`妥当な整数$は ⇒ ❝- を［ 伴わないならば 1 ／ 伴うならば −1 ］ × `Base10$( その中の数字~列 ) を表現する。 ◎ A valid integer without a U+002D HYPHEN-MINUS (-) prefix represents the number that is represented in base ten by that string of digits. A valid integer with a U+002D HYPHEN-MINUS (-) prefix represents the number represented in base ten by the string of digits that follows the U+002D HYPHEN-MINUS, subtracted from zero.

`整数として構文解析する@ 規則は、所与の ( 文字列 %入力 ) に対し，［ 整数, ~error ］のいずれかを返す： ◎ The rules for parsing integers are as given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will return either an integer or an error.

1. %位置 ~LET %入力 の先頭の文字を指している`位置~変数$ ◎ Let input be the string being parsed. ◎ Let position be a pointer into input, initially pointing at the start of the string.
2. %符号 ~LET 1 ◎ Let sign have the value "positive".
3. %入力 内の %位置 から`~ASCII空白を読飛ばす$ ◎ Skip ASCII whitespace within input given position.

4. %位置↗ に応じて： ◎ If position is past the end of input, return an error.

   ❝- ◎ If the character indicated by position (the first character) is a U+002D HYPHEN-MINUS character (-):

   1. %符号 ~LET −1 ◎ Let sign be "negative".
   2. %位置 ~INCBY 1 ◎ Advance position to the next character. ◎ If position is past the end of input, return an error.

   ❝+ ◎ Otherwise, if the character indicated by position (the first character) is a U+002B PLUS SIGN character (+):

   1. %位置 ~INCBY 1 （ `+^l は無視されるが適合ではない。） ◎ Advance position to the next character. (The "+" is ignored, but it is not conforming.) ◎ If position is past the end of input, return an error.

5. ~IF［ %位置↗ ~NIN `~ASCII数字$ ］ ⇒ ~RET ~error ◎ If the character indicated by position is not an ASCII digit, then return an error.
6. %値 ~LET %入力 内の %位置 から `~ASCII数字$からなる`符号位置~並びを収集する$ ◎ Collect a sequence of code points that are ASCII digits from input given position, and＼
7. ~RET %符号 × `Base10$( %値 ) ◎ interpret the resulting sequence as a base-ten integer. Let value be that integer. ◎ If sign is "positive", return value, otherwise return the result of subtracting value from zero.

2.3.4.2. 非負~整数

1 個以上の`~ASCII数字$からなる文字列は `妥当な非負~整数@ とされる。 ◎ A string is a valid non-negative integer if it consists of one or more ASCII digits.

`妥当な非負~整数$は、 `Base10$( その数字~列 ) を表現する。 ◎ A valid non-negative integer represents the number that is represented in base ten by that string of digits.

`非負~整数として構文解析する@ 規則は、所与の ( 文字列 %入力 ) に対し，［ 非負~整数, ~error ］のいずれかを返す： ◎ The rules for parsing non-negative integers are as given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will return either zero, a positive integer, or an error.

1. %値 ~LET `整数として構文解析する$( %入力 ) ◎ Let input be the string being parsed. ◎ Let value be the result of parsing input using the rules for parsing integers.
2. ~IF［ %値 ~EQ ~error ］~OR［ %値 ~LT 0 ］ ⇒ ~RET ~error ◎ If value is an error, return an error. ◎ If value is less than zero, return an error.
3. ~RET %値 ◎ Return value.

2.3.4.3. 浮動小数点数

次の並びからなる文字列は、 `妥当な浮動小数点数@ とされる： ◎ A string is a valid floating-point number if it consists of:

1. “符号~部” ： 0 〜 1 個の ❝- ◎ Optionally, a U+002D HYPHEN-MINUS character (-).

2. 次の両方, または片方のみによる並び： ◎ One or both of the following, in the given order:

   1. “整数~部” ： 1 個以上の`~ASCII数字$からなる並び ◎ A series of one or more ASCII digits.

   2. 次の並び： ◎ Both of the following, in the given order:

      1. 1 個の ❝. ◎ A single U+002E FULL STOP character (.).
      2. “小数~部” ： 1 個以上の`~ASCII数字$からなる並び ◎ A series of one or more ASCII digits.

3. “指数~部” ： 空~文字列, または 次の並び： ◎ Optionally:

   1. 1 個の［ ❝e, または ❝E ］ ◎ Either a U+0065 LATIN SMALL LETTER E character (e) or a U+0045 LATIN CAPITAL LETTER E character (E).
   2. “指数~部の符号~部” ： 0 〜 1 個の［ ❝-, または ❝+ ］ ◎ Optionally, a U+002D HYPHEN-MINUS character (-) or U+002B PLUS SIGN character (+).
   3. “指数~部の数字~列” ： 1 個以上の`~ASCII数字$からなる並び ◎ A series of one or more ASCII digits.

注記： Infinity, NaN（ Not-a-Number ）いずれの値も，`妥当な浮動小数点数$ではない。 ◎ The Infinity and Not-a-Number (NaN) values are not valid floating-point numbers.

注記： `妥当な浮動小数点数$の概念は、概して，作者に許容されるものを制約する利用に限られる。 一方で、~UAに課される要件には，`浮動小数点数として構文解析する$規則が利用される（例： `progress$e 要素の `max$a 属性 ）。 しかしながら，一部の事例では、文字列が`妥当な浮動小数点数$かどうか検査することも~UA要件に含まれる（例： `Number$st 状態にある `input$e 要素~用の 値の消毒 ／ `srcset^a 属性を 構文解析する ~algo）。 ◎ The valid floating-point number concept is typically only used to restrict what is allowed for authors, while the user agent requirements use the rules for parsing floating-point number values below (e.g., the max attribute of the progress element). However, in some cases the user agent requirements include checking if a string is a valid floating-point number (e.g., the value sanitization algorithm for the Number state of the input element, or the parse a srcset attribute algorithm).

実数 %n に対する `浮動小数点数として最良の表現@ は、 `ToString$jA( %n ) を走らせて得られる文字列である。 `ToString()^jA 抽象演算の結果は一意に決定されるとは限らない — 特定0の値に対する `ToString()^jA の結果として複数の文字列が可能な場合、~UAは常に同じ結果を返さ~MUST（他の~UAは相違する値を利用するかもしれないが）。 ◎ The best representation of the number n as a floating-point number is the string obtained from running ToString(n). The abstract operation ToString is not uniquely determined. When there are multiple possible strings that could be obtained from ToString for a particular value, the user agent must always return the same string for that value (though it may differ from the value used by other user agents).

`浮動小数点数として構文解析する@ 規則は、所与の ( 文字列 %入力 ) に対し，［ 実数, ~error ］のいずれかを返す： ◎ The rules for parsing floating-point number values are as given in the following algorithm. This algorithm must be aborted at the first step that returns something. This algorithm will return either a number or an error.

1. %位置 ~LET %入力 の先頭の文字を指している`位置~変数$ ◎ Let input be the string being parsed. ◎ Let position be a pointer into input, initially pointing at the start of the string. ◎ Let value have the value 1. ◎ Let divisor have the value 1. ◎ Let exponent have the value 1.
2. %入力 内の %位置 から`~ASCII空白を読飛ばす$ ◎ Skip ASCII whitespace within input given position. ◎ If position is past the end of input, return an error. ↓
3. %符号 ~LET ［ %位置↗ ~EQ ❝- ならば −1 ／ ~ELSE_ 1 ］ ◎ If the character indicated by position is a U+002D HYPHEN-MINUS character (-): • Change value and divisor to −1. • Advance position to the next character. • If position is past the end of input, return an error. ↓
4. ~IF［ %位置↗ ~IN { ❝-, ❝+ } ］ ⇒ %位置 ~INCBY 1 （ `+^l は適合でないが無視される） ◎ Otherwise, if the character indicated by position (the first character) is a U+002B PLUS SIGN character (+): • Advance position to the next character. (The "+" is ignored, but it is not conforming.) • If position is past the end of input, return an error.
5. ~IF［ %位置↗ ~NIN `~ASCII数字$ ］ ⇒ ~IF［ %位置↗ ~NEQ ❝. ］~OR［ ( %位置 + 1 )↗ ~NIN `~ASCII数字$ ］ ⇒ ~RET ~error ◎ ↑↓
6. %値 ~LET %入力 内の %位置 から `~ASCII数字$からなる`符号位置~並びを収集する$ ◎ ↓
7. %値 ~SET `Base10$( %値 ) ◎ If the character indicated by position is a U+002E FULL STOP (.), and that is not the last character in input, and the character after the character indicated by position is an ASCII digit, then set value to zero and jump to the step labeled fraction. ◎ If the character indicated by position is not an ASCII digit, then return an error. ◎ Collect a sequence of code points that are ASCII digits from input given position, and interpret the resulting sequence as a base-ten integer. Multiply value by that integer. ◎ If position is past the end of input, jump to the step labeled conversion.

8. ~IF［ %位置↗ ~EQ ❝. ]：

   1. %位置 ~INCBY 1
   2. %小数~部 ~LET %入力 内の %位置 から `~ASCII数字$からなる`符号位置~並びを収集する$
   3. %値 ~INCBY `Frac10$( %小数~部 )
   ◎ Fraction: If the character indicated by position is a U+002E FULL STOP (.), run these substeps: • Advance position to the next character. • If position is past the end of input, or if the character indicated by position is not an ASCII digit, U+0065 LATIN SMALL LETTER E (e), or U+0045 LATIN CAPITAL LETTER E (E), then jump to the step labeled conversion. • If the character indicated by position is a U+0065 LATIN SMALL LETTER E character (e) or a U+0045 LATIN CAPITAL LETTER E character (E), skip the remainder of these substeps. •• Fraction loop: Multiply divisor by ten. ••Add the value of the character indicated by position, interpreted as a base-ten digit (0..9) and divided by divisor, to value. ••Advance position to the next character. ••If position is past the end of input, then jump to the step labeled conversion. ••If the character indicated by position is an ASCII digit, jump back to the step labeled fraction loop in these substeps.

9. ~IF［ %位置↗ ~IN { ❝e, ❝E } ］： ◎ If the character indicated by position is U+0065 (e) or a U+0045 (E), then:

   1. %位置 ~INCBY 1 ◎ Advance position to the next character. ◎ If position is past the end of input, then jump to the step labeled conversion.
   2. %指数 ~SET ［ %位置↗ ~EQ ❝- ならば −1 ／ ~ELSE_ 1 ］ ◎ If the character indicated by position is a U+002D HYPHEN-MINUS character (-): • Change exponent to −1. • Advance position to the next character. • If position is past the end of input, then jump to the step labeled conversion.
   3. ~IF［ %位置↗ ~IN { ❝-, ❝+ } ］ ⇒ %位置 ~INCBY 1 ◎ Otherwise, if the character indicated by position is a U+002B PLUS SIGN character (+): • Advance position to the next character. • If position is past the end of input, then jump to the step labeled conversion.
   4. %冪 ~LET %入力 内の %位置 から `~ASCII数字$からなる`符号位置~並びを収集する$ ◎ ↓
   5. %指数 ~SET %指数 × `Base10$( %冪 ) ◎ If the character indicated by position is not an ASCII digit, then jump to the step labeled conversion. ◎ Collect a sequence of code points that are ASCII digits from input given position, and interpret the resulting sequence as a base-ten integer. Multiply exponent by that integer.
   6. %値 ~SET %値 × ( 10 の %指数 乗 ) ◎ Multiply value by ten raised to the exponentth power.
10. %値 ~SET %値 × %符号 ◎ ↑↑
11. %S ~LET ［［ 有限 IEEE 754 倍精度 浮動小数点数の集合 ］から −0 を除いた集合 ］に 2 個の特別な値［ %max ~EQ ( 2 の 1024 乗 ), %min ~EQ −( 2 の 1024 乗 ) ］を追加した集合 ◎ Conversion: Let S be the set of finite IEEE 754 double-precision floating-point values except −0, but with two special values added: 21024 and −21024.
12. %結果 ~LET %S 内の数であって， %値 に最も近いもの — ここで、%値 が %S 内の 2 個の数に等しく近い場合は、仮数が偶数である方を選ぶ（この目的においては、 %max, %min の仮数は偶数と見なす）。 ◎ Let rounded-value be the number in S that is closest to value, selecting the number with an even significand if there are two equally close values. (The two special values 21024 and −21024 are considered to have even significands for this purpose.)
13. ~IF［ %結果 ~IN { %max, %min } ］ ⇒ ~RET ~error ◎ If rounded-value is 21024 or −21024, return an error.
14. ~RET %結果 ◎ Return rounded-value.

【 この訳では、等価な結果が得られるように，原文の~algoをかなり簡約している。 】

2.3.4.4. 百分率, 長さ

`寸法~値として構文解析する@ 規則は、所与の ( 文字列 %入力 ) に対し，［ ( 実数, 種別 ) の組, ~error ］のいずれかを返す — ここで、実数は 0.0 以上, 種別は［ `百分率^i, `長さ^i ］のいずれかである： ◎ The rules for parsing dimension values are as given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will return either a number greater than or equal to 0.0, or an error; if a number is returned, then it is further categorized as either a percentage or a length.

1. %位置 ~LET %入力 の先頭の文字を指している`位置~変数$ ◎ Let input be the string being parsed. ◎ Let position be a pointer into input, initially pointing at the start of the string.
2. %入力 内の %位置 から`~ASCII空白を読飛ばす$ ◎ Skip ASCII whitespace within input given position.
3. ~IF［ %位置↗ ~EQ ❝+ ］ ⇒ %位置 ~INCBY 1 ◎ If position is past the end of input, return an error. ◎ If the character indicated by position is a U+002B PLUS SIGN character (+), advance position to the next character.
4. ~IF［ %位置↗ ~NIN `~ASCII数字$ ］ ⇒ ~RET ~error ◎ If position is past the end of input, return an error. ◎ If the character indicated by position is not an ASCII digit, then return an error.
5. %値 ~LET %入力 内の %位置 から `~ASCII数字$からなる`符号位置~並びを収集する$ ◎ Collect a sequence of code points that are ASCII digits from input given position, and＼
6. %値 ~SET `Base10$( %値 ) ◎ interpret the resulting sequence as a base-ten integer. Let value be that number. ◎ If position is past the end of input, return value as a length. ↓

7. ~IF［ %位置↗ ~EQ ❝. ］： ◎ If the character indicated by position is a U+002E FULL STOP character (.):

   1. %位置 ~INCBY 1 ◎ Advance position to the next character.
   2. ~IF［ %位置↗ ~NIN `~ASCII数字$ ］ ⇒ ~RET ( %値, `長さ^i ) ◎ If position is past the end of input, or if the character indicated by position is not an ASCII digit, then return value as a length.
   3. %小数~部 ~LET %入力 内の %位置 から `~ASCII数字$からなる`符号位置~並びを収集する$ ◎ ↓
   4. %値 ~INCBY `Frac10$( %小数~部 ) ◎ Let divisor have the value 1. ◎ Fraction loop: Multiply divisor by ten. ◎ Add the value of the character indicated by position, interpreted as a base-ten digit (0..9) and divided by divisor, to value. ◎ Advance position to the next character. ◎ If position is past the end of input, then return value as a length. ◎ If the character indicated by position is an ASCII digit, return to the step labeled fraction loop in these substeps.
8. ~IF［ %位置↗ ~EQ ❝% ］ ⇒ ~RET ( %値, `百分率^i ) ◎ If position is past the end of input, return value as a length. ◎ If the character indicated by position is a U+0025 PERCENT SIGN character (%), return value as a percentage.
9. ~RET ( %値, `長さ^i ) ◎ Return value as a length.

2.3.4.5. 非~zeroの百分率と長さ

`非~zero寸法~値として構文解析する@ 規則は、所与の ( 文字列 %入力 ) に対し，［［ ( 0.0 以上の実数, 種別（`百分率^i または `長さ^i ）) の組 ］, ~error ］のいずれかを返す： ◎ The rules for parsing nonzero dimension values are as given in the following algorithm. When invoked, the steps must be followed in the order given, aborting at the first step that returns a value. This algorithm will return either a number greater than 0.0, or an error; if a number is returned, then it is further categorized as either a percentage or a length.

1. %V ~LET `寸法~値として構文解析する$( %入力 ) ◎ Let input be the string being parsed. ◎ Let value be the result of parsing input using the rules for parsing dimension values.
2. ~IF［ %V ~EQ ~error ］~OR ［ %V ~EQ 0 ］ ⇒ ~RET ~error ◎ If value is an error, return an error. ◎ If value is zero, return an error.
3. ~RET %V ◎ If value is a percentage, return value as a percentage. ◎ Return value as a length.

2.3.4.6. 浮動小数点数~list

❝, で互いに区切られた， 0 個以上の`妥当な浮動小数点数$からなる文字列は、 `妥当な浮動小数点数~list@ とされる。 区切りには他の文字（`~ASCII空白$など）は含まない。 加えて，許容される 浮動小数点数の個数 には、制約が課されることもある。 ◎ A valid list of floating-point numbers is a number of valid floating-point numbers separated by U+002C COMMA characters, with no other characters (e.g. no ASCII whitespace). In addition, there might be restrictions on the number of floating-point numbers that can be given, or on the range of values allowed.

`浮動小数点数~listとして構文解析する@ 規則は、所与の ( 文字列 %入力 ) に対し，次に従う： ◎ The rules for parsing a list of floating-point numbers are as follows:

1. %位置 ~LET %入力 の先頭の文字を指している`位置~変数$ ◎ Let input be the string being parsed. ◎ Let position be a pointer into input, initially pointing at the start of the string.
2. %実数~list ~LET 空~list — この~listが~algoの結果になる。 ◎ Let numbers be an initially empty list of floating-point numbers. This list will be the result of this algorithm.
3. %区切子 ~LET { `~ASCII空白$, ❝,, ❝; } ◎ ↓
4. %入力 内の %位置 から %区切子 からなる`符号位置~並びを収集する$ — これは、頭部の区切子を読飛ばす。 ◎ Collect a sequence of code points that are ASCII whitespace, U+002C COMMA, or U+003B SEMICOLON characters from input given position. This skips past any leading delimiters.

5. ~WHILE ( %位置↗ ~NEQ ε )： ◎ While position is not past the end of input:

   1. %入力 内の %位置 から { %区切子, `~ASCII数字$, ❝., ❝- } 以外の`符号位置~並びを収集する$ — これは、頭部の無用な文字~並びを読飛ばす。 ◎ Collect a sequence of code points that are not ASCII whitespace, U+002C COMMA, U+003B SEMICOLON, ASCII digits, U+002E FULL STOP, or U+002D HYPHEN-MINUS characters from input given position. This skips past leading garbage.
   2. %実数~文字列 ~LET %入力 内の %位置 から %区切子 以外の`符号位置~並びを収集する$ ◎ Collect a sequence of code points that are not ASCII whitespace, U+002C COMMA, or U+003B SEMICOLON characters from input given position, and let unparsed number be the result.
   3. %実数 ~LET `浮動小数点数として構文解析する$( %実数~文字列 ) ◎ Let number be the result of parsing unparsed number using the rules for parsing floating-point number values.
   4. ~IF［ %実数 ~EQ ~error ］ ⇒ %実数 ~SET 0 ◎ If number is an error, set number to zero.
   5. %実数~list に %実数 を付加する ◎ Append number to numbers.
   6. %入力 内の %位置 から %区切子 からなる`符号位置~並びを収集する$ — これは、次の区切子を読飛ばす。 ◎ Collect a sequence of code points that are ASCII whitespace, U+002C COMMA, or U+003B SEMICOLON characters from input given position. This skips past the delimiter.
6. ~RET %実数~list ◎ Return numbers.

2.3.4.7. 寸法~list

【 この節に与える `寸法~listとして構文解析する@ 規則を利用しているものは、廃用にされた `frameset$e 要素の `cols^a, `rows^a 属性しかないので（ 参照元 ），和訳は省略する。 】

2.3.5.1. 年月t

`年月t@ （ month ）は、日t 成分を伴わない（日t 成分は ε にされた）`日付$である。 ◎ A month consists of a specific proleptic-Gregorian date with no time-zone information and no date information beyond a year and a month. [GREGORIAN]

【 原文の語 “month” には、暗黙的に年tも含まれている（ “暦の中のある年tの中のある月t” ）。 単独の月t 成分と混同されないよう、この定義を指す month は， “年月t” と表記することにする。 】

次の並びからなる文字列は、`年月t$を表現している `妥当な年月t文字列@ とされる： ◎ A string is a valid month string representing a year year and month month if it consists of the following components in the given order:

1. 年t 成分を表現する，次を満たす文字列 %年t ⇒ ［ %年t は 4 個以上の`~ASCII数字$並びである ］~AND［ `Base10$( %年t ) ~NEQ 0 ］ ◎ Four or more ASCII digits, representing year, where year > 0
2. ❝- ◎ A U+002D HYPHEN-MINUS character (-)
3. 月t 成分を表現する，次を満たす文字列 %月t ⇒ ［ %月t は 2 個の`~ASCII数字$並びである ］~AND［ `Base10$( %月t ) ~IN { 1 〜 12 } ］ ◎ Two ASCII digits, representing the month month, in the range 1 ≤ month ≤ 12

`年月t文字列を構文解析する@ 規則は、所与の ( 文字列 %入力 ) に対し，［ `年月t$, ε ］のいずれかを返す： ◎ The rules to parse a month string are as follows. This will return either a year and month, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.

1. %位置 ~LET %入力 の先頭の文字を指している`位置~変数$ ◎ Let input be the string being parsed. ◎ Let position be a pointer into input, initially pointing at the start of the string.
2. %日付 ~LET `年月t成分を構文解析する$ ◎ ↓
3. ~IF［ %日付 ~EQ ε ］ ⇒ ~RET ε ◎ Parse a month component to obtain year and month. If this returns nothing, then fail.
4. ~IF［ %位置↗ ~NEQ ε ］ ⇒ ~RET ε ◎ If position is not beyond the end of input, then fail.
5. ~RET %日付 ◎ Return year and month.

所与の %入力 内の %位置 から `年月t成分を構文解析する@ 規則は、［ `年月t$, ε ］のいずれかを返す。 ◎ The rules to parse a month component, given an input string and a position, are as follows. This will return either a year and a month, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.

1. %年t ~LET %入力 内の %位置 から `~ASCII数字$からなる`符号位置~並びを収集する$ ◎ Collect a sequence of code points that are ASCII digits from input given position.＼
2. ~IF［ %年t の文字~数 ~LT 4 ］ ⇒ ~RET ε ◎ If the collected sequence is not at least four characters long, then fail.＼
3. %年t ~SET `Base10$( %年t ) ◎ Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the year.
4. ~IF［ %年t ~EQ 0 ］ ⇒ ~RET ε ◎ If year is not a number greater than zero, then fail.
5. ~IF［ %位置↗ ~NEQ ❝- ］ ⇒ ~RET ε ◎ If position is beyond the end of input or if the character at position is not a U+002D HYPHEN-MINUS character, then fail.＼
6. %位置 ~INCBY 1 ◎ Otherwise, move position forwards one character.
7. %月t ~LET %入力 内の %位置 から `~ASCII数字$からなる`符号位置~並びを収集する$ ◎ Collect a sequence of code points that are ASCII digits from input given position.＼
8. ~IF［ %月t の文字~数 ~NEQ 2 ］ ⇒ ~RET ε ◎ If the collected sequence is not exactly two characters long, then fail.＼
9. %月t数 ~SET `Base10$( %月t ) ◎ Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the month.
10. ~IF［ %月t数 ~NIN { 1 〜 12 } ］ ⇒ ~RET ε ◎ If month is not a number in the range 1 ≤ month ≤ 12, then fail.
11. ~RET `日付$( %年t数, %月t数, ε ) ◎ Return year and month.

2.3.5.2. 日付

次の並びからなる文字列は、`日付$を表現している `妥当な日付~文字列@ とされる： ◎ A string is a valid date string representing a year year, month month, and day day if it consists of the following components in the given order:

1. ( 年t, 月t ) 成分を表現する，`妥当な年月t文字列$ ◎ A valid month string, representing year and month
2. 1 個の ❝- ◎ A U+002D HYPHEN-MINUS character (-)
3. 日t 成分を表現する，次を満たす文字列 %日t ⇒ ［ 2 個の`~ASCII数字$並びである ］~AND［ `Base10$( %日t ) ~IN { 1 〜 `月tの日t数$( %年t数, %月t数 ) } ］ ◎ Two ASCII digits, representing day, in the range 1 ≤ day ≤ maxday where maxday is the number of days in the month month and year year

`日付~文字列を構文解析する@ 規則は、所与の ( 文字列 %入力 ) に対し，［ `日付$, ε ］のいずれかを返す： ◎ The rules to parse a date string are as follows. This will return either a date, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.

1. %位置 ~LET %入力 の先頭の文字を指している`位置~変数$ ◎ Let input be the string being parsed. ◎ Let position be a pointer into input, initially pointing at the start of the string.
2. %日付 ~LET `日付~成分を構文解析する$ ◎ Parse a date component to obtain year, month, and day.＼
3. ~IF［ %日付 ~EQ ε ］ ⇒ ~RET ε ◎ If this returns nothing, then fail.
4. ~IF［ %位置↗ ~NEQ ε ］ ⇒ ~RET ε ◎ If position is not beyond the end of input, then fail.
5. ~RET %日付 ◎ Let date be the date with year year, month month, and day day. ◎ Return date.

所与の %入力 内の %位置 から `日付~成分を構文解析する@ 規則は、［ `日付$, ε ］のいずれかを返す： ◎ The rules to parse a date component, given an input string and a position, are as follows. This will return either a year, a month, and a day, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.

1. %日付 ~LET `年月t成分を構文解析する$ ◎ Parse a month component to obtain year and month.＼
2. ~IF［ %日付 ~EQ ε ］ ⇒ ~RET ε ◎ If this returns nothing, then fail.
3. %最大日数 ~LET `月tの日t数$( %日付 の年t 成分, %日付 の月t 成分 ) ◎ Let maxday be the number of days in month month of year year.
4. ~IF［ %位置↗ ~NEQ ❝- ］ ⇒ ~RET ε ◎ If position is beyond the end of input or if the character at position is not a U+002D HYPHEN-MINUS character, then fail.＼
5. %位置 ~INCBY 1 ◎ Otherwise, move position forwards one character.
6. %日t ~LET %入力 内の %位置 から `~ASCII数字$からなる`符号位置~並びを収集する$ ◎ Collect a sequence of code points that are ASCII digits from input given position.＼
7. ~IF［ %日t の文字~数 ~NEQ 2 ］ ⇒ ~RET ε ◎ If the collected sequence is not exactly two characters long, then fail.＼
8. %日t数 ~SET `Base10$( %日t ) ◎ Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the day.
9. ~IF［ %日t数 ~NIN { 1 〜 %最大日数 } ］ ⇒ ~RET ε ◎ If day is not a number in the range 1 ≤ day ≤ maxday, then fail.
10. %日付 の 日t 成分 ~SET %日t数 ◎ ↓
11. ~RET %日付 ◎ Return year, month, and day.

2.3.5.3. 月日t

`月日t@ （ yearless date, “年なし日付” ）は、年t 成分を伴わない（年t 成分は ε にされた）`日付$である。 ◎ A yearless date consists of a Gregorian month and a day within that month, but with no associated year. [GREGORIAN]

【 この訳では、他と表記法を一貫させるため， “月日t” と表記する。 】

次の並びからなる文字列は、`月日t$を表現している `妥当な月日t文字列@ とされる： ◎ A string is a valid yearless date string representing a month month and a day day if it consists of the following components in the given order:

1. 0 個または 2 個の ❝- ◎ Optionally, two U+002D HYPHEN-MINUS characters (-)
2. 月t 成分を表現する，次を満たす文字列 %月t ⇒ ［ %月t は 2 個の`~ASCII数字$並びである ］~AND［ `Base10$( %月t ) ~IN { 1 〜 12 } ］ ◎ Two ASCII digits, representing the month month, in the range 1 ≤ month ≤ 12
3. 1 個の ❝- ◎ A U+002D HYPHEN-MINUS character (-)
4. 日t 成分を表現する，次を満たす文字列 %日t ⇒ ［ %日t は 2 個の`~ASCII数字$並びである ］~AND［ `Base10$( %日t ) ~IN { 1 〜 `月tの日t数$( ε, `Base10$( %月t ) ) } ］ ◎ Two ASCII digits, representing day, in the range 1 ≤ day ≤ maxday where maxday is the number of days in the month month and any arbitrary leap year (e.g. 4 or 2000)

注記： 言い換えれば、［ %月t ~EQ `02^l ］ならば、年t数が閏~年tであったかのように，日t数は 29 もとり得る。 ◎ In other words, if the month is "02", meaning February, then the day can be 29, as if the year was a leap year.

`月日t文字列を構文解析する@ 規則は、所与の ( 文字列 %入力 ) に対し，［ `月日t$, ε ］のいずれかを返す： ◎ The rules to parse a yearless date string are as follows. This will return either a month and a day, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.

1. %位置 ~LET %入力 の先頭の文字を指している`位置~変数$ ◎ Let input be the string being parsed. ◎ Let position be a pointer into input, initially pointing at the start of the string.
2. %日付 ~LET `月日t成分を構文解析する$ ◎ Parse a yearless date component to obtain month and day.＼
3. ~IF［ %日付 ~EQ ε ］ ⇒ ~RET ε ◎ If this returns nothing, then fail.
4. ~IF［ %位置↗ ~NEQ ε ］ ⇒ ~RET ε ◎ If position is not beyond the end of input, then fail.
5. ~RET %日付 ◎ Return month and day.

所与の %入力 内の %位置 から `月日t成分を構文解析する@ 規則は、［ `月日t$, ε ］のいずれかを返す： ◎ The rules to parse a yearless date component, given an input string and a position, are as follows. This will return either a month and a day, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.

1. %seq ~LET %入力 内の %位置 から ❝- からなる`符号位置~並びを収集する$ ◎ Collect a sequence of code points that are U+002D HYPHEN-MINUS characters (-) from input given position.＼
2. ~IF［ %seq の文字~数 ~NIN { 0, 2 } ］ ⇒ ~RET ε ◎ If the collected sequence is not exactly zero or two characters long, then fail.
3. %月t ~LET %入力 内の %位置 から `~ASCII数字$からなる`符号位置~並びを収集する$ ◎ Collect a sequence of code points that are ASCII digits from input given position.＼
4. ~IF［ %月t の文字~数 ~NEQ 2 ］ ⇒ ~RET ε ◎ If the collected sequence is not exactly two characters long, then fail.＼
5. %月t数 ~SET `Base10$( %月t ) ◎ Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the month.
6. ~IF［ %月t数 ~NIN { 1 〜 12 } ］ ⇒ ~RET ε ◎ If month is not a number in the range 1 ≤ month ≤ 12, then fail. ◎ Let maxday be the number of days in month month of any arbitrary leap year (e.g. 4 or 2000).
7. ~IF［ %位置↗ ~NEQ ❝- ］ ⇒ ~RET ε ◎ If position is beyond the end of input or if the character at position is not a U+002D HYPHEN-MINUS character, then fail.＼
8. %位置 ~INCBY 1 ◎ Otherwise, move position forwards one character.
9. %日t ~LET %入力 内の %位置 から `~ASCII数字$からなる`符号位置~並びを収集する$ ◎ Collect a sequence of code points that are ASCII digits from input given position.＼
10. ~IF［ %日t の文字~数 ~NEQ 2 ］ ⇒ ~RET ε ◎ If the collected sequence is not exactly two characters long, then fail.＼
11. %日t数 ~SET `Base10$( %日t ) ◎ Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the day.
12. ~IF［ %日t数 ~NIN { 1 〜 `月tの日t数$( ε, %月t数 ) } ］ ⇒ ~RET ε ◎ If day is not a number in the range 1 ≤ day ≤ maxday, then fail.
13. ~RET `日付$( ε, %月t数, %日t数 ) ◎ Return month and day.

2.3.5.4. 時刻

次の並びからなる文字列は、`時刻$を表現している `妥当な時刻~文字列@ とされる： ◎ A string is a valid time string representing an hour hour, a minute minute, and a second second if it consists of the following components in the given order:

1. 時t 成分を表現する，次を満たす文字列 %時t ⇒ ［ %時t は 2 個の`~ASCII数字$並びである ］~AND［ `Base10$( %時t ) ~IN { 0 〜 23 } ］ ◎ Two ASCII digits, representing hour, in the range 0 ≤ hour ≤ 23
2. 1 個の ❝: ◎ A U+003A COLON character (:)
3. 分t 成分を表現する，次を満たす文字列 %分t ⇒ ［ %分t は 2 個の`~ASCII数字$並びである ］~AND［ `Base10$( %分t ) ~IN { 0 〜 59 } ］ ◎ Two ASCII digits, representing minute, in the range 0 ≤ minute ≤ 59

4. 空~文字列（秒t 成分 0 を表現する）, または 秒t 成分を表現する次の並び： ◎ If second is nonzero, or optionally if second is zero:

   1. 1 個の ❝: ◎ A U+003A COLON character (:)
   2. 秒t 成分の整数~部を表現する，次を満たす文字列 %秒t ⇒ ［ %秒t は 2 個の`~ASCII数字$並びである ］~AND［ `Base10$( %秒t ) ~IN { 0 〜 59 } ］ ◎ Two ASCII digits, representing the integer part of second, in the range 0 ≤ s ≤ 59

   3. 空~文字列（ 秒t 成分は整数である）, または 秒tの小数~部を表現する 次の並び： ◎ If second is not an integer, or optionally if second is an integer:

      1. 1 個の ❝. ◎ A U+002E FULL STOP character (.)
      2. 1 〜 3 個の`~ASCII数字$ ◎ One, two, or three ASCII digits, representing the fractional part of second

注記： 秒t 成分は 60, 61 にはなり得ないので、閏~秒tは表現できない。 ◎ The second component cannot be 60 or 61; leap seconds cannot be represented.

【 秒t 成分の小数~部は、`妥当な時刻~文字列$としては 3 桁までにされているが，以下の構文解析-規則の中では 上限はない。 】

`時刻~文字列を構文解析する@ 規則は、所与の ( 文字列 %入力 ) に対し，［ `時刻$, ε ］のいずれかを返す： ◎ The rules to parse a time string are as follows. This will return either a time, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.

1. %位置 ~LET %入力 の先頭の文字を指している`位置~変数$ ◎ Let input be the string being parsed. ◎ Let position be a pointer into input, initially pointing at the start of the string.
2. %時刻 ~LET `時刻~成分を構文解析する$ ◎ Parse a time component to obtain hour, minute, and second.＼
3. ~IF［ %時刻 ~EQ ε ］ ⇒ ~RET ε ◎ If this returns nothing, then fail.
4. ~IF［ %位置↗ ~NEQ ε ］ ⇒ ~RET ε ◎ If position is not beyond the end of input, then fail.
5. ~RET %時刻 ◎ Let time be the time with hour hour, minute minute, and second second. ◎ Return time.

所与の %入力 内の %位置 から `時刻~成分を構文解析する@ 規則は、［ `時刻$, ε ］のいずれかを返す： ◎ The rules to parse a time component, given an input string and a position, are as follows. This will return either an hour, a minute, and a second, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.

1. %時t ~LET %入力 内の %位置 から `~ASCII数字$からなる`符号位置~並びを収集する$ ◎ Collect a sequence of code points that are ASCII digits from input given position.＼
2. ~IF［ %時t の文字~数 ~NEQ 2 ］ ⇒ ~RET ε ◎ If the collected sequence is not exactly two characters long, then fail.＼
3. %時t数 ~SET `Base10$( %時t ) ◎ Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the hour.
4. ~IF［ %時t数 ~NIN { 0 〜 23 } ］ ⇒ ~RET ε ◎ If hour is not a number in the range 0 ≤ hour ≤ 23, then fail.
5. ~IF［ %位置↗ ~NEQ ❝: ］ ⇒ ~RET ε ◎ If position is beyond the end of input or if the character at position is not a U+003A COLON character, then fail.＼
6. %位置 ~INCBY 1 ◎ Otherwise, move position forwards one character.
7. %分t ~LET %入力 内の %位置 から `~ASCII数字$からなる`符号位置~並びを収集する$ ◎ Collect a sequence of code points that are ASCII digits from input given position.＼
8. ~IF［ %分t の文字~数 ~NEQ 2 ］ ⇒ ~RET ε ◎ If the collected sequence is not exactly two characters long, then fail.＼
9. %分t数 ~SET `Base10$( %分t ) ◎ Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the minute.
10. ~IF［ %分t数 ~NIN { 0 〜 59 } ］ ⇒ ~RET ε ◎ If minute is not a number in the range 0 ≤ minute ≤ 59, then fail.
11. %秒t数 ~LET 0 ◎ Let second be 0.

12. ~IF［ %位置↗ ~EQ ❝: ］： ◎ If position is not beyond the end of input and the character at position is U+003A (:), then:

    1. %位置 ~INCBY 1 ◎ Advance position to the next character in input.
    2. ~IF［ %位置↗ ~NIN `~ASCII数字$ ］~OR［ ( %位置 + 1 )↗ ~NIN `~ASCII数字$ ］ ⇒ ~RET ε ◎ If position is beyond the end of input, or at the last character in input, or if the next two characters in input starting at position are not both ASCII digits, then fail.
    3. %秒t数 ~SET `Base10$( ［ %位置↗, ( %位置 + 1 )↗ ］並びからなる文字列 ) ◎ ↓
    4. %位置 ~INCBY 2 ◎ ↓
    5. %小数~部 ~LET %入力 内の %位置 から { `~ASCII数字$, ❝. } からなる`符号位置~並びを収集する$ ◎ Collect a sequence of code points that are either ASCII digits or U+002E FULL STOP characters from input given position.＼

    6. ~IF［ %小数~部 ~NEQ 空~文字列 ］：

       1. ~IF［ %小数~部 の先頭の文字 ~NEQ ❝. ］ ⇒ ~RET ε
       2. %小数~部 から先頭の文字を除去する
       3. ~IF［ %小数~部 ~EQ 空~文字列 ］~OR［ %小数~部 に ❝. が含まれている ］ ⇒ ~RET ε
       4. %秒t数 ~INCBY `Frac10$( %小数~部 )
       ◎ If the collected sequence is three characters long, or if it is longer than three characters long and the third character is not a U+002E FULL STOP character, or if it has more than one U+002E FULL STOP character, then fail. Otherwise, interpret the resulting sequence as a base-ten number (possibly with a fractional part). Set second to that number.
13. ~IF［ %秒t数 ~LT 0 ］~OR［ 60 ~LTE %秒t数 ］ ⇒ ~RET ε ◎ If second is not a number in the range 0 ≤ second < 60, then fail.
14. ~RET `時刻$( %時t数, %分t数, %秒t数 ) ◎ Return hour, minute, and second.

2.3.5.5. 局所的~日時

`局所的~日時@ （ local date and time ）は、時間帯は伴わない， ( `日付$, `時刻$ ) 成分の組からなる。 `GREGORIAN$r 形式的には、偏差~成分が ε にされた`日時$として表される。 ◎ A local date and time consists of a specific proleptic-Gregorian date, consisting of a year, a month, and a day, and a time, consisting of an hour, a minute, a second, and a fraction of a second, but expressed without a time zone. [GREGORIAN]

次の並びからなる文字列は、`局所的~日時$を表現している `妥当な局所的~日時~文字列@ とされる： ◎ A string is a valid local date and time string representing a date and time if it consists of the following components in the given order:

1. 日付 成分を表現する，`妥当な日付~文字列$ ◎ A valid date string representing the date
2. 1 個の［ ❝T, または `0020^U SPACE ］ ◎ A U+0054 LATIN CAPITAL LETTER T character (T) or a U+0020 SPACE character
3. 時刻 成分を表現する，`妥当な時刻~文字列$ ◎ A valid time string representing the time

`妥当な局所的~日時~文字列$は、［ その時刻 成分を表現する文字列が，それが表現する時刻を可能な限り最短の文字列で表現する ］ならば、 `妥当な正規化-済み局所的~日時~文字列@ とされる（例えば，時刻の 秒t 成分が~zeroならば、秒t 成分を表現する文字列を まるごと省略する）。 ◎ A string is a valid normalized local date and time string representing a date and time if it consists of the following components in the given order: • A valid date string representing the date • A U+0054 LATIN CAPITAL LETTER T character (T) • A valid time string representing the time, expressed as the shortest possible string for the given time (e.g. omitting the seconds component entirely if the given time is zero seconds past the minute)

`局所的~日時~文字列を構文解析する@ 規則は、所与の ( 文字列 %入力 ) に対し，［ `局所的~日時$, ε ］のいずれかを返す： ◎ The rules to parse a local date and time string are as follows. This will return either a date and time, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.

1. %位置 ~LET %入力 の先頭の文字を指している`位置~変数$ ◎ Let input be the string being parsed. ◎ Let position be a pointer into input, initially pointing at the start of the string.
2. %日付 ~LET `日付~成分を構文解析する$ ◎ Parse a date component to obtain year, month, and day.＼
3. ~IF［ %日付 ~EQ ε ］ ⇒ ~RET ε ◎ If this returns nothing, then fail.
4. ~IF［ %位置↗ ~NIN { ❝T, `0020^U SPACE } ］ ⇒ ~RET ε ◎ If position is beyond the end of input or if the character at position is neither a U+0054 LATIN CAPITAL LETTER T character (T) nor a U+0020 SPACE character, then fail.＼
5. %位置 ~INCBY 1 ◎ Otherwise, move position forwards one character.
6. %時刻 ~LET `時刻~成分を構文解析する$ ◎ Parse a time component to obtain hour, minute, and second.＼
7. ~IF［ %時刻 ~EQ ε ］ ⇒ ~RET ε ◎ If this returns nothing, then fail.
8. ~IF［ %位置↗ ~NEQ ε ］ ⇒ ~RET ε ◎ If position is not beyond the end of input, then fail.
9. ~RET `日時$( %日付, %時刻, ε ) ◎ Let date be the date with year year, month month, and day day. ◎ Let time be the time with hour hour, minute minute, and second second. ◎ Return date and time.

2.3.5.6. 時間帯

次のいずれかで与えられる文字列は、 偏差を表現している `妥当な偏差~文字列@ とされる： ◎ A string is a valid time-zone offset string representing a time-zone offset if it consists of either:

• 時間帯が~UTC 【すなわち，偏差( 0, 0 )】 の場合に限り ⇒ 1 個の ❝Z ◎ A U+005A LATIN CAPITAL LETTER Z character (Z), allowed only if the time zone is UTC

• または、次の並びからなる文字列： ◎ Or, the following components, in the given order:

  1. 偏差の各~成分の符号を表現する， ❝+ , または ❝- — ただし，偏差の両~成分とも~zeroの場合、後者は許容されない。 ◎ Either a U+002B PLUS SIGN character (+) or, if the time-zone offset is not zero, a U+002D HYPHEN-MINUS character (-), representing the sign of the time-zone offset
  2. 偏差の時t 成分を表現する，次を満たす文字列 %時t ⇒ ［ %時t は 2 個の`~ASCII数字$並びである ］~AND［ `Base10$( %時t ) ~IN { 0 〜 23 } ］ ◎ Two ASCII digits, representing the hours component hour of the time-zone offset, in the range 0 ≤ hour ≤ 23
  3. 0 〜 1 個の ❝: ◎ Optionally, a U+003A COLON character (:)
  4. 偏差の分t 成分を表現する，次を満たす文字列 %分t ⇒ ［ %分t は 2 個の`~ASCII数字$並びである ］~AND［ `Base10$( %分t ) ~IN { 0 〜 59 } ］ ◎ Two ASCII digits, representing the minutes component minute of the time-zone offset, in the range 0 ≤ minute ≤ 59

注記： この形式は、範囲 { −23:59 〜 +23:59 } の偏差を許容する。 今現在，実施においては、実際の時間帯の範囲は { −12:00 〜 +14:00 } であり，実際の時間帯の分t 成分は、常に ［ 00, 30, 45 ］のいずれかにされている。 しかしながら、永劫にそうあり続ける保証はない — 時間帯は政治的駆引きにも利用されており、気まぐれな政治的裁定の対象になるので。 ◎ This format allows for time-zone offsets from -23:59 to +23:59. Right now, in practice, the range of offsets of actual time zones is -12:00 to +14:00, and the minutes component of offsets of actual time zones is always either 00, 30, or 45. There is no guarantee that this will remain so forever, however, since time zones are used as political footballs and are thus subject to very whimsical policy decisions.

注記： 偏差を［ 公式的な時間帯の制定~以前の歴史的~時刻 ］と併用する際の詳細については、下の`大域的~日時$ 節における用法についての注記, および例も見よ。 ◎ See also the usage notes and examples in the global date and time section below for details on using time-zone offsets with historical times that predate the formation of formal time zones.

`偏差~文字列を構文解析する@ 規則は、所与の ( 文字列 %入力 ) に対し，［ 偏差, ε ］のいずれかを返す： ◎ The rules to parse a time-zone offset string are as follows. This will return either a time-zone offset, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.

1. %位置 ~LET %入力 の先頭の文字を指している`位置~変数$ ◎ Let input be the string being parsed. ◎ Let position be a pointer into input, initially pointing at the start of the string.
2. %偏差 ~LET `偏差~成分を構文解析する$ ◎ Parse a time-zone offset component to obtain timezonehours and timezoneminutes.＼
3. ~IF［ %偏差 ~EQ ε ］ ⇒ ~RET ε ◎ If this returns nothing, then fail.
4. ~IF［ %位置↗ ~NEQ ε ］ ⇒ ~RET ε ◎ If position is not beyond the end of input, then fail.
5. ~RET %偏差 ◎ Return the time-zone offset that is timezonehours hours and timezoneminutes minutes from UTC.

所与の %入力 内の %位置 から `偏差~成分を構文解析する@ 規則は、［ `偏差$, ε ］のいずれかを返す： ◎ The rules to parse a time-zone offset component, given an input string and a position, are as follows. This will return either time-zone hours and time-zone minutes, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.

1. %符号 ~LET %位置↗ ◎ ↓
2. ~IF［ %符号 ~NIN { ❝+, ❝-, ❝Z } ］ ⇒ ~RET ε ◎ ↓↓
3. %位置 ~INCBY 1 ◎ ↓
4. ~IF［ %符号 ~EQ ❝Z ］ ⇒ ~RET `偏差$( 0, 0 ) ◎ If the character at position is a U+005A LATIN CAPITAL LETTER Z character (Z), then: • Let timezonehours be 0. • Let timezoneminutes be 0. • Advance position to the next character in input.
5. %時t ~LET %入力 内の %位置 から `~ASCII数字$からなる`符号位置~並びを収集する$ ◎ ↓
6. %分t ~LET ε ◎ ↑↑Otherwise, if the character at position is either a U+002B PLUS SIGN (+) or a U+002D HYPHEN-MINUS (-), then: ◎ ↓If the character at position is a U+002B PLUS SIGN (+), let sign be "positive". Otherwise, it's a U+002D HYPHEN-MINUS (-); let sign be "negative". ◎ ↑Advance position to the next character in input. ◎ Collect a sequence of code points that are ASCII digits from input given position. Let s be the collected sequence.

7. ~IF［ %時t の文字~数 ~EQ 2 ］：

   1. ~IF［ %位置↗ ~NEQ ❝: ］ ⇒ ~RET ε
   2. %位置 ~INCBY 1
   3. %分t ~SET %入力 内の %位置 から `~ASCII数字$からなる`符号位置~並びを収集する$
   4. ~IF［ %分t の文字~数 ~NEQ 2 ］ ⇒ ~RET ε
   ◎ If s is exactly two characters long, then: • Interpret s as a base-ten integer. Let that number be the timezonehours. • If position is beyond the end of input or if the character at position is not a U+003A COLON character, then fail. Otherwise, move position forwards one character. • Collect a sequence of code points that are ASCII digits from input given position. If the collected sequence is not exactly two characters long, then fail. Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the timezoneminutes.
8. ~ELIF［ %時t の文字~数 ~EQ 4 ］ ⇒ ( %時t, %分t ) ~SET %時t の ( 最初の 2 文字, 最後の 2 文字 ) ◎ If s is exactly four characters long, then: • Interpret the first two characters of s as a base-ten integer. Let that number be the timezonehours. • Interpret the last two characters of s as a base-ten integer. Let that number be the timezoneminutes.
9. ~ELSE ⇒ ~RET ε ◎ Otherwise, fail.
10. ( %時t数, %分t数 ) ~LET ( `Base10$( %時t ), `Base10$( %分t ) ) ◎ ↑
11. ~IF［ %時t数 ~NIN { 0 〜 23 } ］~OR［ %分t数 ~NIN { 0 〜 59 } ］ ⇒ ~RET ε ◎ If timezonehours is not a number in the range 0 ≤ timezonehours ≤ 23, then fail. ◎ If sign is "negative", then negate timezonehours. ◎ If timezoneminutes is not a number in the range 0 ≤ timezoneminutes ≤ 59, then fail. ◎ If sign is "negative", then negate timezoneminutes.
12. ~IF［ %符号 ~EQ ❝- ］ ⇒ ~RET `偏差$( %時t数 × −1, %分t数 × −1 ) ◎ ↑
13. ~RET `偏差$( %時t数, %分t数 ) ◎ ↑↑Otherwise, fail. ◎ Return timezonehours and timezoneminutes.

2.3.5.7. 大域的~日時

次の並びからなる文字列は、`大域的~日時$を表現している `妥当な大域的~日時~文字列@ とされる： ◎ A string is a valid global date and time string representing a date, time, and a time-zone offset if it consists of the following components in the given order:

1. 日付 成分を表現する，`妥当な日付~文字列$ ◎ A valid date string representing the date
2. 1 個の［ ❝T または `0020^U SPACE ］ ◎ A U+0054 LATIN CAPITAL LETTER T character (T) or a U+0020 SPACE character
3. 時刻 成分を表現する，`妥当な時刻~文字列$ ◎ A valid time string representing the time
4. 偏差 成分を表現する，`妥当な偏差~文字列$ ◎ A valid time-zone offset string representing the time-zone offset

`大域的~日時~文字列を構文解析する@ 規則は、所与の ( 文字列 %入力 ) に対し，［ `大域的~日時$, ε ］のいずれかを返す： ◎ The rules to parse a global date and time string are as follows. This will return either a time in UTC, with associated time-zone offset information for round-tripping or display purposes, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.

1. %位置 ~LET %入力 の先頭の文字を指している`位置~変数$ ◎ Let input be the string being parsed. ◎ Let position be a pointer into input, initially pointing at the start of the string.
2. %日付 ~LET `日付~成分を構文解析する$ ◎ Parse a date component to obtain year, month, and day.＼
3. ~IF［ %日付 ~EQ ε ］ ⇒ ~RET ε ◎ If this returns nothing, then fail.
4. ~IF［ %位置↗ ~NIN { ❝T, `0020^U SPACE } ］ ⇒ ~RET ε ◎ If position is beyond the end of input or if the character at position is neither a U+0054 LATIN CAPITAL LETTER T character (T) nor a U+0020 SPACE character, then fail.＼
5. %位置 ~INCBY 1 ◎ Otherwise, move position forwards one character.
6. %時刻 ~LET `時刻~成分を構文解析する$ ◎ Parse a time component to obtain hour, minute, and second.＼
7. ~IF［ %時刻 ~EQ ε ］ ⇒ ~RET ε ◎ If this returns nothing, then fail.
8. ~IF［ %位置↗ ~EQ ε ］ ⇒ ~RET ε ◎ If position is beyond the end of input, then fail.
9. %偏差 ~LET `偏差~成分を構文解析する$ ◎ Parse a time-zone offset component to obtain timezonehours and timezoneminutes.＼
10. ~IF［ %偏差 ~EQ ε ］ ⇒ ~RET ε ◎ If this returns nothing, then fail.
11. ~IF［ %位置↗ ~NEQ ε ］ ⇒ ~RET ε ◎ If position is not beyond the end of input, then fail.
12. ( %日付, %時刻 ) ~LET ( %日付, %時刻 ) から %偏差 を減算した結果† — この結果が~UTC時間帯における時刻を表す。 ◎ Let time be the moment in time at year year, month month, day day, hours hour, minute minute, second second, subtracting timezonehours hours and timezoneminutes minutes. That moment in time is a moment in the UTC time zone.
13. ~RET `日時$( %日付, %時刻, %偏差 ) ◎ Let timezone be timezonehours hours and timezoneminutes minutes from UTC. ◎ Return time and timezone.

【† “減算する” ための具体的な~algoは、この仕様には述べられていない。 %入力 においては，年t 成分に対する ~zeroは許容されていない が、減算した結果の年tは，~zeroになり得る。 】

2.3.5.8. 年週t

注記： 年末年始の特定0の日tにおける週年tと，`遡及~Gregorian暦$における その日tを包含する年tとは、異なることもある。 週年t %Y における最初の週tは、~Gregorian年t %Y の最初の火曜を包含する週tである 【そうなるように、年週tは定義されている】 。 ◎ The week-year number of a particular day can be different than the number of the year that contains that day in the proleptic Gregorian calendar. The first week in a week-year y is the week that contains the first Thursday of the Gregorian year y.

注記： 現代の目的においては、ここに定義される`年週t$は、 `ISO8601$r に定義される週tと等価になる。 ◎ For modern purposes, a week as defined here is equivalent to ISO weeks as defined in ISO 8601. [ISO8601]

次の並びからなる文字列は、`年週t$を表現している `妥当な年週t文字列@ とされる： ◎ A string is a valid week string representing a week-year year and week week if it consists of the following components in the given order:

1. 年週tの週年t 成分を表現する，次を満たす文字列 %週年t ⇒ ［ %週年t は 4 個以上の`~ASCII数字$並びである ］~AND［ `Base10$( %週年t ) ~NEQ 0 ］ ◎ Four or more ASCII digits, representing year, where year > 0
2. 1 個の ❝- ◎ A U+002D HYPHEN-MINUS character (-)
3. 1 個の ❝W ◎ A U+0057 LATIN CAPITAL LETTER W character (W)
4. 年週tの週t 成分を表現する，次を満たす文字列 %週t ⇒ ［ %週t は 2 個の`~ASCII数字$並びである ］~AND［ `Base10$( %週t ) ~IN { 1 〜 `週t数$( %週年t が表現する週年t ) } ］ ◎ Two ASCII digits, representing the week week, in the range 1 ≤ week ≤ maxweek, where maxweek is the week number of the last day of week-year year

`年週t文字列を構文解析する@ 規則は、所与の ( 文字列 %入力 ) に対し，［ `年週t$, ε ］のいずれかを返す： ◎ The rules to parse a week string are as follows. This will return either a week-year number and week number, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.

1. %位置 ~LET %入力 の先頭の文字を指している`位置~変数$ ◎ Let input be the string being parsed. ◎ Let position be a pointer into input, initially pointing at the start of the string.
2. %年t ~LET %入力 内の %位置 から `~ASCII数字$からなる`符号位置~並びを収集する$ ◎ Collect a sequence of code points that are ASCII digits from input given position.＼
3. ~IF［ %年t の文字~数 ~LT 4 ］ ⇒ ~RET ε ◎ If the collected sequence is not at least four characters long, then fail.＼
4. %年t数 ~SET `Base10$( %年t ) ◎ Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the year.
5. ~IF［ %年t数 ~EQ 0 ］ ⇒ ~RET ε ◎ If year is not a number greater than zero, then fail.
6. ~IF［ %位置↗ ~NEQ ❝- ］ ⇒ ~RET ε ◎ If position is beyond the end of input or if the character at position is not a U+002D HYPHEN-MINUS character, then fail.＼
7. %位置 ~INCBY 1 ◎ Otherwise, move position forwards one character.
8. ~IF［ %位置↗ ~NEQ ❝W ］ ⇒ ~RET ε ◎ If position is beyond the end of input or if the character at position is not a U+0057 LATIN CAPITAL LETTER W character (W), then fail.＼
9. %位置 ~INCBY 1 ◎ Otherwise, move position forwards one character.
10. %週t ~LET %入力 内の %位置 から `~ASCII数字$からなる`符号位置~並びを収集する$ ◎ Collect a sequence of code points that are ASCII digits from input given position.＼
11. ~IF［ %週t の文字~数 ~NEQ 2 ］ ⇒ ~RET ε ◎ If the collected sequence is not exactly two characters long, then fail.＼
12. %週t数 ~SET `Base10$( %週t ) ◎ Otherwise, interpret the resulting sequence as a base-ten integer. Let that number be the week.
13. ~IF［ %週t数 ~NIN { 1 〜 `週t数$( %年t数 ) } ］ ⇒ ~RET ε ◎ Let maxweek be the week number of the last day of year year. ◎ If week is not a number in the range 1 ≤ week ≤ maxweek, then fail.
14. ~IF［ %位置↗ ~NEQ ε ］ ⇒ ~RET ε ◎ If position is not beyond the end of input, then fail.
15. ~RET `年週t$( %年t数, %週t数 ) ◎ Return the week-year number year and the week number week.

2.3.5.9. 時間長

`時間長@ （ duration ）は、（負でない）秒t数である。 ◎ A duration consists of a number of seconds.

注記： 月t数と秒t数は，比較-可能でないので（月tは精確な秒t数を表さない — その正確な長さは，測定し始める精確な日tに依存する期間である）、この仕様にて定義される`時間長$には，月tは含められない（したがって月t数 12 に等価な年tも）。 特定の秒t数を述べる時間長のみ，記述できる。 ◎ Since months and seconds are not comparable (a month is not a precise number of seconds, but is instead a period whose exact length depends on the precise day from which it is measured) a duration as defined in this specification cannot include months (or years, which are equivalent to twelve months). Only durations that describe a specific number of seconds can be described.

次のいずれかからなる文字列は、`時間長$を表現している `妥当な時間長~文字列@ とされる： ◎ A string is a valid duration string representing a duration t if it consists of either of the following:

• 文字 ❝P に［ 次の並びが成す空でない文字列 ］を付加して得られる文字列 — その中で与えられる ( 日t数, 時t数, 分t数, 秒t数 ) に対する ( 日t数 × 86400 + 時t数 × 3600 + 分t数 × 60 + 秒t数 ) が、`時間長$を与える（どの空~文字列も 0 に解釈する）： ◎ A literal U+0050 LATIN CAPITAL LETTER P character followed by one or more of the following subcomponents, in the order given, where the number of days, hours, minutes, and seconds corresponds to the same number of seconds as in t:

  1. 日t数を表現する，空~文字列 または 次の並び ⇒＃ 1 個以上の`~ASCII数字$, 1 個の ❝D ◎ One or more ASCII digits followed by a U+0044 LATIN CAPITAL LETTER D character, representing a number of days.

  2. 空~文字列 — ( 時t数, 分t数, 秒t数 ) いずれも 0 を表現する — または、文字 ❝T に［ 次の並びが成す空でない文字列 ］を付加して得られる文字列： ◎ A U+0054 LATIN CAPITAL LETTER T character followed by one or more of the following subcomponents, in the order given:

     1. 時t数を表現する，空~文字列 または 次の並び ⇒＃ 1 個以上の`~ASCII数字$, 1 個の ❝H ◎ One or more ASCII digits followed by a U+0048 LATIN CAPITAL LETTER H character, representing a number of hours.
     2. 分t数を表現する，空~文字列 または 次の並び ⇒＃ 1 個以上の`~ASCII数字$, 1 個の ❝M ◎ One or more ASCII digits followed by a U+004D LATIN CAPITAL LETTER M character, representing a number of minutes.

     3. 秒t数を表現する，空~文字列 または 次の並び： ◎ The following components:

        1. 1 個以上の`~ASCII数字$ ◎ One or more ASCII digits, representing a number of seconds.
        2. 秒tの小数~部を表現する，空~文字列 または 次の並び ⇒＃ 1 個の ❝., 1 〜 3 個の`~ASCII数字$ ◎ Optionally, a U+002E FULL STOP character (.) followed by one, two, or three ASCII digits, representing a fraction of a second.
        3. 1 個の ❝S ◎ A U+0053 LATIN CAPITAL LETTER S character.

  注記： これは、この仕様にて 日時に関係する他の各種 小構文に定義されるように， `ISO8601$r にて定義される各種~形式のいずれかに基づく。 ◎ This, as with a number of other date- and time-related microsyntaxes defined in this specification, is based on one of the formats defined in ISO 8601. [ISO8601]

• 任意の順序による， 1 個以上の各種 `時間長~成分$ — それぞれの`時間長~成分の縮尺$は互いに異なるような。 それぞれが表現する秒t数の総和が、`時間長$を与える。 ◎ One or more duration time components, each with a different duration time component scale, in any order; the sum of the represented seconds being equal to the number of seconds in t.

  次の並びからなる文字列が `時間長~成分@ （ duration time component ）とされる： ◎ A duration time component is a string consisting of the following components:

  1. 0 個以上の`~ASCII空白$ ◎ Zero or more ASCII whitespace.
  2. 1 個以上の `~ASCII数字$ — 時間~単位~数を表現し、 ( この数 × 下に指定される`時間長~成分の縮尺$ ) が，この時間長~成分の秒t数を表現する。 ◎ One or more ASCII digits, representing a number of time units, scaled by the duration time component scale specified (see below) to represent a number of seconds.
  3. `時間長~成分の縮尺$ ~EQ 1 の場合（すなわち，単位は秒t）に限り ⇒ 空~文字列, または 秒tの小数~部を表現する次の並び ⇒＃ 1 個の ❝., 1 〜 3 個の`~ASCII数字$ ◎ If the duration time component scale specified is 1 (i.e. the units are seconds), then, optionally, a U+002E FULL STOP character (.) followed by one, two, or three ASCII digits, representing a fraction of a second.
  4. 0 個以上の`~ASCII空白$ ◎ Zero or more ASCII whitespace.

  5. 次の表の最初の列に与えるいずれかの文字 — 同じ行の “縮尺” の列が `時間長~成分の縮尺@ を与える：

     文字	単位	縮尺
     ❝W, ❝w	週t	604800
     ❝D, ❝d	日t	86400
     ❝H, ❝h	時t	3600
     ❝M, ❝m	分t	60
     ❝S, ❝s	秒t	1

     ◎ One of the following characters, representing the duration time component scale of the time unit used in the numeric part of the duration time component: • U+0057 LATIN CAPITAL LETTER W character • U+0077 LATIN SMALL LETTER W character •• Weeks. The scale is 604800. • U+0044 LATIN CAPITAL LETTER D character • U+0064 LATIN SMALL LETTER D character •• Days. The scale is 86400. • U+0048 LATIN CAPITAL LETTER H character • U+0068 LATIN SMALL LETTER H character •• Hours. The scale is 3600. • U+004D LATIN CAPITAL LETTER M character • U+006D LATIN SMALL LETTER M character •• Minutes. The scale is 60. • U+0053 LATIN CAPITAL LETTER S character • U+0073 LATIN SMALL LETTER S character •• Seconds. The scale is 1.
  6. 0 個以上の`~ASCII空白$ ◎ Zero or more ASCII whitespace.

  注記： これは、~ISO8601のどの形式に基づくものでもない。 これは、~ISO8601時間長~形式より，人から読み易い代替を与えるために意図されている。 ◎ This is not based on any of the formats in ISO 8601. It is intended to be a more human-readable alternative to the ISO 8601 duration format.

`時間長~文字列を構文解析する@ 規則は、所与の ( 文字列 %入力 ) に対し，［ `時間長$, ε ］のいずれかを返す： ◎ The rules to parse a duration string are as follows. This will return either a duration or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.

1. %位置 ~LET %入力 の先頭の文字を指している`位置~変数$ ◎ Let input be the string being parsed. ◎ Let position be a pointer into input, initially pointing at the start of the string.
2. ( %月t数, %秒t数, %空 ) ~LET ( 0, 0, ~T ) ◎ Let months, seconds, and component count all be zero.

3. %M一義化子 ~LET `分t^i ◎ Let M-disambiguator be minutes.

   注記： %M一義化子 が他にとり得る値は `月t^i である。 これは、月t数と分t数に同じ単位を利用している ~ISO8601時間長における "M" 単位を一義化するために利用される。 月t数は %入力 に許容されないが、将来との互換性をとるため, および 他の文脈においては妥当になるような~ISO8601時間長の誤解釈を避けるために構文解析される。 ◎ This flag's other value is months. It is used to disambiguate the "M" unit in ISO8601 durations, which use the same unit for months and minutes. Months are not allowed, but are parsed for future compatibility and to avoid misinterpreting ISO8601 durations that would be valid in other contexts.

4. %入力 内の %位置 から`~ASCII空白を読飛ばす$ ◎ Skip ASCII whitespace within input given position. ◎ If position is past the end of input, then fail.

5. ~IF［ %位置↗ ~EQ ❝P ］：

   1. %位置 ~INCBY 1
   2. %M一義化子 ~SET `月t^i
   3. %入力 内の %位置 から`~ASCII空白を読飛ばす$
   ◎ If the character in input pointed to by position is a U+0050 LATIN CAPITAL LETTER P character, then advance position to the next character, set M-disambiguator to months, and skip ASCII whitespace within input given position.

6. ~WHILE %位置↗ ~NEQ ε： ◎ While true: • Let units be undefined. It will be assigned one of the following values: years, months, weeks, days, hours, minutes, and seconds. • Let next character be undefined. It is used to process characters from the input. • If position is past the end of input, then break.

   1. ( %単位, %縮尺 ) ~LET ( ε, ε ) ◎ ↑

   2. ~IF［ %位置↗ ~EQ ❝T ］：

      1. %位置 ~INCBY 1
      2. %M一義化子 ~SET `分t^i
      3. %入力 内の %位置 から`~ASCII空白を読飛ばす$
      4. ~CONTINUE
      ◎ If the character in input pointed to by position is a U+0054 LATIN CAPITAL LETTER T character, then advance position to the next character, set M-disambiguator to minutes, skip ASCII whitespace within input given position, and continue.
   3. ~IF［ %位置↗ ~NIN { `~ASCII数字$, ❝. } ］ ⇒ ~RET ε ◎ ↓
   4. %N ~LET %入力 内の %位置 から `~ASCII数字$からなる`符号位置~並びを収集する$ ◎ ↓
   5. %N ~SET `Base10$( %N ) ◎ Set next character to the character in input pointed to by position. • If next character is a U+002E FULL STOP character (.), then let N equal zero. (Do not advance position. That is taken care of below.) • Otherwise, if next character is an ASCII digit, then collect a sequence of code points that are ASCII digits from input given position, interpret the resulting sequence as a base-ten integer, and let N be that number. • Otherwise next character is not part of a number; fail. • If position is past the end of input, then fail.

   6. ~IF［ %位置↗ ~EQ ❝. ］： ◎ Set next character to the character in input pointed to by position, and this time advance position to the next character. (If next character was a U+002E FULL STOP character (.) before, it will still be that character this time.) ◎ If next character is U+002E (.), then:

      1. %位置 ~INCBY 1
      2. %s ~LET %入力 内の %位置 から`~ASCII数字$からなる`符号位置~並びを収集する$ ◎ Collect a sequence of code points that are ASCII digits from input given position. Let s be the resulting sequence.
      3. ~IF［ %s ~EQ 空~文字列 ］ ⇒ ~RET ε ◎ If s is the empty string, then fail.
      4. %N ~INCBY `Frac10$( %s ) ◎ Let length be the number of characters in s. ◎ Let fraction be the result of interpreting s as a base-ten integer, and then dividing that number by 10length. ◎ Increment N by fraction.
      5. %入力 内の %位置 から`~ASCII空白を読飛ばす$ ◎ Skip ASCII whitespace within input given position.
      6. %s ~SET %位置↗
      7. %位置 ~INCBY 1
      8. ~IF［ %s ~NIN { ❝S, ❝s } ］ ⇒ ~RET ε ◎ If position is past the end of input, then fail. ◎ Set next character to the character in input pointed to by position, and advance position to the next character. ◎ If next character is neither a U+0053 LATIN CAPITAL LETTER S character nor a U+0073 LATIN SMALL LETTER S character, then fail.
      9. %単位 ~SET `秒t^i ◎ Set units to seconds.

   7. ~ELSE： ◎ Otherwise:

      1. %入力 内の %位置 から`~ASCII空白を読飛ばす$ ◎ If next character is ASCII whitespace, then skip ASCII whitespace within input given position, set next character to the character in input pointed to by position, and advance position to the next character.

      2. ( %単位, %縮尺, %M一義化子 ) ~SET %位置↗ に応じて，次の表で与えられる値：

         %位置↗	%単位	%縮尺	%M一義化子
         ❝Y, ❝y	`年t^i	ε	`月t^i
         ❝M, ❝m	%M一義化子	60	%M一義化子
         ❝W, ❝w	`週t^i	604800	`分t^i
         ❝D, ❝d	`日t^i	86400	`分t^i
         ❝H, ❝h	`時t^i	3600	`分t^i
         ❝S, ❝s	`秒t^i	1	`分t^i
         その他	ε	ε	ε

         ◎ If next character is a U+0059 LATIN CAPITAL LETTER Y character, or a U+0079 LATIN SMALL LETTER Y character, set units to years and set M-disambiguator to months. ◎ If next character is a U+004D LATIN CAPITAL LETTER M character or a U+006D LATIN SMALL LETTER M character, and M-disambiguator is months, then set units to months. ◎ If next character is a U+0057 LATIN CAPITAL LETTER W character or a U+0077 LATIN SMALL LETTER W character, set units to weeks and set M-disambiguator to minutes. ◎ If next character is a U+0044 LATIN CAPITAL LETTER D character or a U+0064 LATIN SMALL LETTER D character, set units to days and set M-disambiguator to minutes. ◎ If next character is a U+0048 LATIN CAPITAL LETTER H character or a U+0068 LATIN SMALL LETTER H character, set units to hours and set M-disambiguator to minutes. ◎ If next character is a U+004D LATIN CAPITAL LETTER M character or a U+006D LATIN SMALL LETTER M character, and M-disambiguator is minutes, then set units to minutes. ◎ If next character is a U+0053 LATIN CAPITAL LETTER S character or a U+0073 LATIN SMALL LETTER S character, set units to seconds and set M-disambiguator to minutes.
      3. %位置 ~INCBY 1 ◎ ↑
      4. ~IF［ %単位 ~EQ ε ］ ⇒ ~RET ε ◎ Otherwise if next character is none of the above characters, then fail.
   8. %空 ~SET ~F ◎ Increment component count.

   9. %単位 に応じて：

      `年t^i

      %月t数 ~INCBY %N × 12

      `月t^i

      %月t数 ~INCBY %N

      その他

      %秒t数 ~INCBY %N × %縮尺

      ◎ Let multiplier be 1. ◎ If units is years, multiply multiplier by 12 and set units to months. ◎ If units is months, add the product of N and multiplier to months. ◎ Otherwise: • If units is weeks, multiply multiplier by 7 and set units to days. • If units is days, multiply multiplier by 24 and set units to hours. • If units is hours, multiply multiplier by 60 and set units to minutes. • If units is minutes, multiply multiplier by 60 and set units to seconds. • Forcibly, units is now seconds. Add the product of N and multiplier to seconds.
   10. %入力 内の %位置 から`~ASCII空白を読飛ばす$ ◎ Skip ASCII whitespace within input given position.
7. ~IF［ %空 ~EQ ~T ］ ⇒ ~RET ε ◎ If component count is zero, fail.
8. ~IF［ %月t数 ~NEQ 0 ］ ⇒ ~RET ε ◎ If months is not zero, fail.
9. ~RET `時間長$( %秒t数 ) ◎ Return the duration consisting of seconds seconds.

2.3.5.10. 漠然とした時刻

【 この節に与える定義を利用しているものは、［ `ins^e ／ `del^e ］要素の `datetime$a 属性しかない（特に， `time$e 要素の同名の属性には関わらない）。 】

次のいずれかの文字列は、 `妥当な省略あり日時~文字列@ とされる： ◎ A string is a valid date string with optional time if it is also one of the following:

• `妥当な日付~文字列$ ◎ A valid date string
• `妥当な大域的~日時~文字列$ ◎ A valid global date and time string

`省略あり日時~文字列を構文解析する@ 規則は、所与の ( 文字列 %入力 ) に対し，［ `日付$, `時刻$, `大域的~日時$, ε ］のいずれかを返す： ◎ The rules to parse a date or time string are as follows. The algorithm will return either a date, a time, a global date and time, or nothing. If at any point the algorithm says that it "fails", this means that it is aborted at that point and returns nothing.

1. %位置 ~LET %入力 の先頭の文字を指している`位置~変数$ ◎ Let input be the string being parsed. ◎ Let position be a pointer into input, initially pointing at the start of the string.
2. %開始-位置- ~SET %位置 と同じ位置 ◎ Set start position to the same position as position.
3. %時刻 ~LET ε ◎ Set the date present and time present flags to true.
4. %日付 ~LET `日付~成分を構文解析する$ ◎ Parse a date component to obtain year, month, and day. If this fails, then set the date present flag to false.

5. ~IF［ %日付 ~EQ ε ］~OR［ %位置↗ ~IN { ❝T, `0020^U SPACE } ］：

   1. ~IF［ %日付 ~EQ ε ］ ⇒ %位置 ~SET %開始-位置
   2. ~ELSE ⇒ %位置 ~INCBY 1
   3. %時刻 ~LET `時刻~成分を構文解析する$
   4. ~IF［ %時刻 ~EQ ε ］ ⇒ ~RET ε
   ◎ If date present is true, and position is not beyond the end of input, and the character at position is either a U+0054 LATIN CAPITAL LETTER T character (T) or a U+0020 SPACE character, then advance position to the next character in input. ◎ Otherwise, if date present is true, and either position is beyond the end of input or the character at position is neither a U+0054 LATIN CAPITAL LETTER T character (T) nor a U+0020 SPACE character, then set time present to false. ◎ Otherwise, if date present is false, set position back to the same position as start position. ◎ If the time present flag is true, then parse a time component to obtain hour, minute, and second. If this returns nothing, then fail.

6. ~IF［ %日付 ~NEQ ε ］~AND［ %時刻 ~NEQ ε ］：

   1. %偏差 ~LET `偏差~成分を構文解析する$
   2. ~IF［ %偏差 ~EQ ε ］ ⇒ ~RET ε
   ◎ If the date present and time present flags are both true, but position is beyond the end of input, then fail. ◎ If the date present and time present flags are both true, parse a time-zone offset component to obtain timezonehours and timezoneminutes. If this returns nothing, then fail.
7. ~IF［ %位置↗ ~NEQ ε ］ ⇒ ~RET ε ◎ If position is not beyond the end of input, then fail.
8. ~IF［ %時刻 ~EQ ε ］ ⇒ ~RET %日付 ◎ If the date present flag is true and the time present flag is false, then let date be the date with year year, month month, and day day, and return date.
9. ~IF［ %日付 ~EQ ε ］ ⇒ ~RET %時刻 ◎ Otherwise, if the time present flag is true and the date present flag is false, then let time be the time with hour hour, minute minute, and second second, and return time.
10. ( %日付, %時刻 ) ~LET ( %日付, %時刻 ) から %偏差 を減算した結果 ◎ Otherwise, let time be the moment in time at year year, month month, day day, hours hour, minute minute, second second, subtracting timezonehours hours and timezoneminutes minutes, that moment in time being a moment in the UTC time zone;＼
11. ~RET `日時$( %日付, %時刻, %偏差 ) ◎ let timezone be timezonehours hours and timezoneminutes minutes from UTC; and return time and timezone.