Sources & illustrations

These primary references support the background explanations. Read the source for details, updates and exceptions.

Background reading

• IANA: Time Zone Database
• NIST: daylight-saving time
• MDN: Intl.DateTimeFormat
• RFC 3339: Gregorian dates and timestamp notation
• ISO: standardized date and time formats
• RFC 5545: calendar event representation
• Python: documented ISO calendar behavior
• MDN: date timestamp units

Original illustrations and examples

The subject illustration and guide diagrams are original vector drawings. Worked examples and practice exercises are original teaching material. They do not represent an experiment or a personal product test. We do not reproduce reference-site articles, photographs, dictionary definitions, music scores or puzzle answers.

Scope

Digital calendar arithmetic and time-zone interpretation. No printable planners, travel itineraries or legal deadline advice. Browser time-zone data can lag rule changes; verify consequential schedules with the organizer or relevant authority.

References checked on 18 October 2026. Product interfaces, regional advice and datasets can change after publication.