Glossary

DTSTART

The iCalendar property carrying an event's start, as either a timezone-anchored instant or a floating date.

DTSTART is where an event's start lives. For timed events it references a timezone (via TZID) or UTC; for all-day events it is a bare date. Its counterpart DTEND is exclusive: the moment the event no longer occupies.

Many interoperability bugs trace to DTSTART handling: missing TZIDs, all-day events written as midnight timestamps, or end times omitted entirely, which some publishers do and importers must repair.