Add AccurateDuration and NominalDuration

scalars/contributed/AlexandreCarlton/accurate-duration.md

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+<!-- cspell:ignore Alexandre -->
+
+# AccurateDuration — GraphQL Custom Scalar
+
+Author - AlexandreCarlton
+
+Date - 2024-03-17
+
+**License and Copyright**
+
+Copyright © GraphQL contributors. This specification is licensed under
+[OWFa 1.0](https://www.openwebfoundation.org/the-agreements/the-owf-1-0-agreements-granted-claims/owfa-1-0).
+
+# Overview
+
+This Scalar represents an exact length in time. It is a refinement of the
+duration as defined by [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) with
+the caveat that it does not support calendar components that would otherwise
+require the knowledge of a date to determine a precise value. As such, the
+following components are excluded:
+
+- calendar year (as this can be potentially a leap year).
+- calendar month as this may contain a variable number of days).
+- calendar day (as this may contain leap seconds by decision of the
+  [Internal Earth Rotation Service](https://en.wikipedia.org/wiki/International_Earth_Rotation_and_Reference_Systems_Service)).
+- calendar week (as this is seven calendar days).
+
+Days (unlike calendar days) are supported under the definition of
+[ISO 31-1](https://en.wikipedia.org/wiki/ISO_31-1): 24 hours.
+
+Negative durations per [ISO 8601-2](https://en.wikipedia.org/wiki/ISO_8601) are
+supported.
+
+# Name
+
+`AccurateDuration`, originating from the wording in
+[ISO 8601](https://en.wikipedia.org/wiki/ISO_8601):
+
+<blockquote>Duration can be expressed by a combination of components with accurate duration (hour, minute and second)
+and components with nominal duration (year, month, week and day).</blockquote>
+
+# Input/Result specification
+
+[ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) defines a duration as either:
+
+- `PnYnMnDTnHnMnS`
+- `PnW`
+
+Instead, the specification `PDTnHnMn.nS` is used, with the further amendments:
+
+- Year/Month/Week components are not supported.
+- Days are considered to be always 24 hours.
+- The entire string may be prefixed with a `-` to signify a negative duration.
+- Each component may be prefixed with a `-` to signify a negative component.
+- The seconds component (and only the seconds component) may have a fractional
+  component of up to 9 digits.
+- Overflowing of components above their maximum (e.g. 60 for a minute) is
+  allowed. For example, `PT90M` is valid and equivalent to `PT1H30M`.
+
+## Positive examples
+
+| String           | Explanation                                              |
+| ---------------- | -------------------------------------------------------- |
+| `PT2M`           | A duration representing 2 minutes.                       |
+| `PT120S`         | A duration representing 120 seconds (2 minutes).         |
+| `PT0.000000001S` | A duration representing 1 nanosecond.                    |
+| `-P1D`           | A duration representing 1 negative day.                  |
+| `P1D-2H`         | A duration representing two hours fewer than a full day. |
+
+## Negative examples
+
+| String            | Explanation                                                     |
+| ----------------- | --------------------------------------------------------------- |
+| `P1Y`             | Calendar years are not supported.                               |
+| `P1M`             | Calendar months are not supported.                              |
+| `P1W`             | Calendar weeks are not supported.                               |
+| `P0.5D`           | Fractional component is only supported for seconds.             |
+| `PT0.0000000001S` | Fractional component in seconds only supports at most 9 digits. |
+| `PTS`             | Digits must precede units.                                      |
+
+# References
+
+- [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601)

scalars/contributed/AlexandreCarlton/nominal-duration.md

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+<!-- cspell:ignore Alexandre -->
+
+# AccurateDuration — GraphQL Custom Scalar
+
+Author - AlexandreCarlton
+
+Date - 2024-03-17
+
+**License and Copyright**
+
+Copyright © GraphQL contributors. This specification is licensed under
+[OWFa 1.0](https://www.openwebfoundation.org/the-agreements/the-owf-1-0-agreements-granted-claims/owfa-1-0).
+
+# Overview
+
+This Scalar represents a length in time in years, months, weeks or days. It is a
+refinement of the duration as defined by
+[ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) with the caveat that it only
+supports calendar components that require the knowledge of the particular
+calendar position with which the duration is being evaluated. As such, only the
+following components are included:
+
+- calendar year (as this can be potentially a leap year).
+- calendar month as this may contain a variable number of days).
+- calendar day (as this may contain leap seconds by decision of the
+  [Internal Earth Rotation Service](https://en.wikipedia.org/wiki/International_Earth_Rotation_and_Reference_Systems_Service)).
+- calendar week (as this is seven calendar days).
+
+Negative durations per [ISO 8601-2](https://en.wikipedia.org/wiki/ISO_8601) are
+supported.
+
+# Name
+
+`NominalDuration`, originating from the wording in
+[ISO 8601](https://en.wikipedia.org/wiki/ISO_8601):
+
+<blockquote>Duration can be expressed by a combination of components with accurate duration (hour, minute and second)
+and components with nominal duration (year, month, week and day).</blockquote>
+
+# Input/Result specification
+
+[ISO 8601](https://en.wikipedia.org/wiki/ISO_8601) defines a duration as either:
+
+- `PnYnMnDTnHnMnS`
+- `PnW`
+
+Instead, the specification `PnYnMnWnD` is used, with the further amendments:
+
+- The entire string may be prefixed with a `-` to signify a negative duration.
+- Each component may be prefixed with a `-` to signify a negative component.
+- A calendar week may be declared alongside calendar year/month/day components.
+
+## Positive examples
+
+| String   | Explanation                                                               |
+| -------- | ------------------------------------------------------------------------- |
+| `P1Y`    | A duration representing a calendar year.                                  |
+| `P2W`    | A duration representing two calendar weeks.                               |
+| `-P1Y2M` | A negative duration representing a calendar year and calendar month.      |
+| `P1Y-2M` | A duration representing a two calendar months fewer than a calendar year. |
+| `P2M3W`  | A duration representing a two calendar months and three calendar weeks.   |
+| `P24M`   | A duration representing a twenty four calendar months.                    |
+
+## Negative examples
+
+| String  | Explanation                              |
+| ------- | ---------------------------------------- |
+| `PT1H`  | Hours are not supported.                 |
+| `PT1M`  | Minutes are not supported.               |
+| `PT1S`  | Seconds are not supported.               |
+| `P1.5Y` | Fractional components are not supported. |
+| `PY`    | Digits must precede units.               |
+
+# References
+
+- [ISO 8601](https://en.wikipedia.org/wiki/ISO_8601)