Conformance
ISO 8601:2019 defines a “profile” as a specification of how the standard is to be used for a particular context. It’s also useful to check what your system supports in order to determine interoperability with other systems.
Key Questions
- Basic
- Date and time can be handled as basic and extended formats.
- Duration can be handled as explicit format.
- Evaluation of Duration
- as per ISO 8601-2:2019 Annex D
- as per ISO 8601-2:2019 Annex D, but always ignoring leap seconds
- as per XML Schema 1.0 and 1.1
- Leap seconds
- Support the input, output and storage of leap seconds.
- Supports conversion between UTC and UT1,
both ways for positive and negative leap seconds.
- Monotonic clock
Some systems assume that events happen in the order in which they are timestamped, forgetting that systems clocks are regularly changed to synchronise with external time sources.- Which clock does your system use ?
- Which time source is this synchronised and how regularly ?
- When system time is regularly updated to an external source, is monotonicity maintained by: slewing, smearing, mapping or other?
- Is monotocity maintained over daylight savings clock changes ?
- When clock changes are forced, is there a requirement to maintain monotonicity ?
- Other Extensions
- Negative, Exponential and Expanded calendar years.
- Seasons, quarter, terms, semesters.
- Grouped time scale units
- Set representation
- Selection from a set
- Explicit representation of date time with designators
- Qualification for uncertain date times
- Unspecified digits
- Extended time interval
- Explicit duration – supporting decimal or negative amounts.
- Recurring time intervals