datestimes

Datestime is a value that encodes both a calendar date and a time of day, representing a precise moment. In many systems this concept is referred to as a datetime, timestamp, or date-time value. The term datestime is not a standard ISO terminology, but may appear in documentation or in API schemas as a field name to emphasize the combined nature of date and time.

Common textual formats follow ISO 8601, such as 2025-12-31T23:59:59Z or 2025-12-31T23:59:59+02:00, optionally with fractional seconds. Numeric representations include seconds since the Unix epoch (1970-01-01 UTC) and its millisecond or nanosecond variants. Databases often provide native types such as DATETIME, TIMESTAMP, or DATE plus TIME, with varying behavior on time zones and precision.

Time zones and precision are important considerations for datestimes. To avoid ambiguity, store times in Coordinated Universal Time (UTC) or include an explicit offset or time zone. Where local time is used, convert to UTC for storage and display localized to the user. Leap seconds and clock drift can also affect precision and interpretation, so systems should document their handling policies.

Uses for datestimes include logging, auditing, event ordering, scheduling, data replication, and version control metadata. Best practices emphasize unambiguous representations, consistent precision, and clear time zone handling to ensure reliable interpretation across systems.

See also: datestamp, timestamp, datetime, timezone, ISO 8601.