UTCn

UTCn is a term used in computing and data-logging to describe a time representation based on Coordinated Universal Time (UTC) that is parameterized by an integer n. In this convention, n denotes the number of fractional-second digits included in the timestamp. UTCn is not an official time standard, but a descriptive shorthand used by some software and documentation to express the intended precision of UTC timestamps.

Format and examples: UTCn timestamps are formatted similarly to ISO 8601, with a decimal point and n digits following the seconds field, and a trailing Z to indicate UTC. Examples: UTC0: 2024-07-20T14:32:07Z; UTC3: 2024-07-20T14:32:07.123Z; UTC9: 2024-07-20T14:32:07.123456789Z.

Rationale and usage: The UTCn convention supports deterministic ordering, fixed-width storage, and consistent parsing across systems that require precise sub-second resolution. It is commonly encountered in logs, event streams, and data interchange where timestamps must be comparable without ambiguity.

Limitations and relationship to standards: As a non-standard convention, UTCn relies on tolerance of different implementations for decimal precision and rounding behavior. It does not modify the rules for leap seconds in UTC, and interoperability may require explicit conversion to a standard timestamp format such as ISO 8601 or RFC 3339. The concept is mainly descriptive rather than normative.

See also: Coordinated Universal Time, ISO 8601, RFC 3339, timestamps, leap seconds.