Format Atlas

Guides

Verifying calendar and contact data with a trial import

After choosing a format, check time interpretation, recurrence, contact fields and duplicate handling in a test environment before migrating existing data.

Which format should you choose?

Choose by the role each file plays in your workflow.

  • Define scope, supported versions and rollback
  • Compare time and field semantics
  • Import into an empty test destination

Define scope, supported versions and rollback

Record calendars and contacts, export time, counts, applications and the vCard VERSION. Back up existing data and originals. Prepare a test environment that will not send invitations or automatically synchronize. File import is not the same as ongoing synchronization.

Compare time and field semantics

Distinguish UTC, times with TZID, floating times and all-day dates; check recurrence exclusions, modified instances and daylight-saving boundaries. VEVENT DTEND is an exclusive end boundary. For contacts, check structured names, multiple phones and emails with types, addresses, photos and referenced URLs. vCard 4.0 uses UTF-8; do not assume older versions follow identical rules.

Import into an empty test destination

Compare sample event occurrences and contact fields, not just counts. Recurrence definitions and expanded occurrence counts differ. Check UID handling, duplicate, update and addition behavior, and lost fields. Record differences before migrating production data.

Formats to consider

iCalendar

Good for: Checking event times, recurrence and exceptions

Less suitable for: Expecting ongoing synchronization from an ICS import

vCard

Good for: Exchanging contact fields using supported versions

Less suitable for: Migrating without checking VERSION or multiple-field support

CSV

Good for: Exchanging lists with explicit column mapping

Less suitable for: Expecting recurrence or multiple contact fields to reconstruct automatically

Before you export

  • Treat phone numbers as text and preserve leading zeros, plus signs and field types. Keep conversion settings and originals.
  • Check sharing scope for attendees, addresses and notes; avoid invitation sends or changes to existing data during testing. Import success does not guarantee every field is retained.

Related comparisons

ICS vs CSVICS represents calendar events and scheduling data with fields for dates, recurrence, time zones, and other event details. CSV stores rows and columns, so calendar applications may require a specific column layout and mapping to import it.VCF vs CSVVCF is used to exchange contact records, while CSV represents tabular data. Choose based on whether contacts will be imported into an address book or organized and processed as a list.

Guides

Choose a calendar or contact file formatUse ICS to import events into a calendar, VCF for contact apps, and CSV when you need to edit a list as a table.Verifying messages after an email migrationAfter choosing a format, record scope and metadata, then compare bodies, attachments and counts in a trial import before migrating the working mailbox.

References and specifications