When a local programme time falls inside a skipped clock hour

Some local labels do not occur on the transition date

When a clock advances, part of the wall-clock night can be skipped. A programme data source that supplies a local time in that missing range needs interpretation or correction; the label alone does not describe a real local instant under the applicable rule.

This is different from a programme starting late. The problem arises before playback: the timestamp itself does not map cleanly to a local moment. A guide can display a plausible time while losing the original source’s intended instant.

Use UTC to compare the boundary

The two UTC instants below are real instants on either side of a New York clock transition in the 2026f rules. Their local labels show the skipped interval.

A manual one-hour shift is not a general parser repair

Moving every programme in a guide by an hour can hide one symptom while changing valid timestamps elsewhere. Preserve the source timestamp, stated zone and intended date, then establish how that source represents the transition. A complete UTC timestamp avoids the missing-local-label ambiguity.

If the programme source publishes a corrected schedule, use that correction. The time-zone database supplies civil rules; it cannot infer which edition or scheduling decision a broadcaster intended from an impossible local label.

Keep errors visible during import

A system importing guide data should distinguish a valid converted time from a timestamp that required a fallback assumption. Recording that distinction makes a later discrepancy explainable. Silently replacing an invalid time can make the guide look complete while concealing uncertainty.

Questions about this guide

Sources and further reading

• IANA 2026f time-zone source