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Welcome to the Temporal-Abstract-Spec wiki

As the Abstract Conceptual Model for Time OGC23-049 is approved and is being published, some of the content below may be unnecessary and could be removed.

Minutes of the OGC Temporal Domain Working Group
We are also experimenting with using an OGC Slack channel #temporal-DWG
Current Workplan
Existing standards:

ISO19111 has largely supplanted the now outdated ISO19108;

ISO8601 is being updated for open ended time intervals;

ISO34000 includes terminology suitable for the relativistic regime, but several different definitions of a timescale.
Restrictive profiles of existing standards:

IETF RFC3339 Date and Time on the Internet: Timestamps is a useful restriction of ISO8601;

W3C Data and Time Format is another restriction of ISO8601.
Useful References
Stakeholders in temporal infrastructure:

ISO established an Ad Hoc group on Time and published a Temporal Vocabulary ISO34000. There is also an approved ISO project to develop tags to indicate a variety of widely used calendars;

OGC Naming Authority has a machinable register of some Temporal Coordinate Reference Systems;

BIPM is responsible for coordinating atomic time across the globe and maintaining a civil Universal Coordinated Time (UTC) which is the basis for the Gregorian Calendar. It also defines the fundamental constants, such as the second, kilogramme and metre;

IERS is responsible for tracking Earth's rotation with respect to the stars and the Sun, and declares when leap seconds should be introduced into UTC so that the Gregorian Calendar maintains consistency with the Earth's rotation with respect to the Sun, to a precision of better than one second. This potential discrepancy is because the second is now defined by atomic clocks rather than a fraction of the rotation period of the Earth.

MISB Moving Imagery Standards Board Processing of moving imagery often needs high precision coordinated time and Chapter 6 in this document defines good or best practice.

IETF has several RFCs that are about time, such as the RFC3339 above, the NTP Network Time Protocol and the recently proposed TZif Time Zone Information Format.
Examples of good and bad practice: See MISB Motion Imagery Handbook, Chapter 6.
Examples or catalogue of temporal systems: See Wikipedia List of Calendars and Current Time Standards
Useful Snippets that may not have made it into the Abstract Conceptual Model for time

Time Scales and Calendars

All defined timescales and calendars, as they are based on physical devices, have a temporal scope; That is, a time interval for which they are valid. Outside of the this interval, people may still choose to use that temporal reference system, but with indeterminate accuracy and precision, and no obvious methods of determining them.