8601RFC

8601RFC, commonly referred to as RFC 8601, is an Internet Engineering Task Force (IETF) specification titled Date and Time Formats. It provides a comprehensive framework for representing dates and times in Internet protocols and data interchange. The document consolidates ISO 8601 notation and supersedes earlier profiles such as RFC 3339, clarifying allowed forms and constraints to improve interoperability.

The specification describes multiple date representations, including calendar dates: YYYY-MM-DD; ordinal dates: YYYY-DDD; and week dates: YYYY-Www-D. It standardizes time values, including hours, minutes, and seconds (HH:MM:SS), with optional fractional seconds. A time zone designator is required for non-UTC representations and can be Z for UTC or an offset in the form ±HH:MM. The recommended extended form, common in practice, uses a T to separate date and time, for example 2024-07-16T12:34:56Z or 2024-07-16T12:34:56+02:00. The specification also notes compatibility with basic forms and defines constraints aimed at interoperability across protocols.

RFC 8601 is widely used in Internet protocols, data formats, and APIs that require precise timestamps. By providing a single, unambiguous set of rules for date-time representations, it harmonizes previous practices and serves as a normative reference for developers and systems that rely on timestamp values. In many environments, RFC 3339 remains in use as a subset, but RFC 8601 offers the broader, more explicit standard for date and time notation.