1Overview

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 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).
• calendar week (as this is seven calendar days).

Negative durations per ISO 8601-2 are supported.

2Recommended name

The recommended name is NominalDuration, 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 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.

4References

• ISO 8601