1Overview

This Scalar represents an exact length in time. It is a refinement of the duration as defined by 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).
• calendar week (as this is seven calendar days).

Days (unlike calendar days) are supported under the definition of ISO 31-1: 24 hours.

Negative durations per ISO 8601-2 are supported.

2Recommended name

The recommended name is AccurateDuration, originating from the wording in ISO 8601:

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).

3Input/Result specification

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.

4References

• ISO 8601