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Review DST gaps, overlaps and UTC offsets

This is a fixed-example checklist. Before handing a time to a schedule or record, confirm the date-specific timezone source and the recipient's interpretation. This page does not fetch real data or a live timezone database.

Fixed example Only five fixed cases are rendered in the browser. There is no timezone API, storage or transmission.

Review points

Example	timezone	Class	Handoff caution
Spring transition	America/New_York	gap	Do not confirm a nonexistent local time
Fall transition	America/New_York	overlap	Confirm which offset is intended
Explicit offset	+09:00	offset	Do not confuse a region with an offset
Non-DST	Asia/Tokyo	non-DST	Do not assume DST rules
Unknown	unknown	fail closed	Do not convert before confirmation