BEGINVCALENDAR

BEGIN:VCALENDAR marks the start of a calendar object in the iCalendar data format. It is defined in RFC 5545 (the iCalendar standard, successor to RFC 2445) and serves as the top-level container for calendar data. A VCALENDAR object begins with the line BEGIN:VCALENDAR and ends with END:VCALENDAR, enclosing a set of global properties and one or more calendar components.

Within a VCALENDAR, common global properties include PRODID (an identifier for the producing system), VERSION (typically 2.0), and CALSCALE (usually GREGORIAN). An optional METHOD property can express the iCalendar method being used (for example, PUBLISH, REQUEST, or REPLY). The VCALENDAR may also include VTIMEZONE components to define time zone information used by events and other components.

The body of a VCALENDAR contains calendar components such as VEVENT (events), VTODO (to-dos), VJOURNAL (journal entries), VFREEBUSY (free/busy information), and VTIMEZONE (time zone definitions). A single VCALENDAR may include multiple VEVENTs or other components. Each component is itself delimited by BEGIN and END lines, for example BEGIN:VEVENT ... END:VEVENT for an event.

Serialization follows the iCalendar syntax: lines are text strings with name-value pairs, encoded in UTF-8 or US-ASCII, and may be folded across multiple lines as specified by the standard. iCalendar data is widely used for exchanging calendar information between applications, enabling calendar sharing, subscription, and synchronization across platforms.

Overall, BEGIN:VCALENDAR encapsulates a calendar’s metadata and content in a standardized, interoperable format suitable for import, export, and exchange of calendar data.