2.2.98 [RFC5545] Section 8.1 iCalendar Media Type Registration

E0001:

The specification states, "The Calendaring and Scheduling Core Object Specification is intended for use as a MIME content-type."

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In addition to handling the MIME content-type, Outlook also registers the .ics and .vcs file extensions. It also registers the webcal:// and webcals:// protocols.

When a .ics or .vcs file is opened, Outlook interprets it as a Calendar folder or a Calendar object, based on the following rules:

  1. If no VEVENT component is found within the first 32 kilobytes of the file, then the file is treated as a Calendar folder.

  2. If an X-MS-OLK-FORCEINSPECTOROPEN property ([MS-OXCICAL] section 2.1.3.1.1.9) is found within the first 32 kilobytes of the file and is set to "TRUE", then the file is treated as a Calendar object.

  3. If there is no X-WR-CALNAME property ([MS-OXCICAL] section 2.1.3.1.1.17) and only one VEVENT component in the first 32 kilobytes of the file, then the file is treated as a Calendar object.

  4. If the METHOD property is set to "REQUEST", "REPLY", or "CANCEL" in the first 32 kilobytes of the file, then the file is treated as a Calendar object.

  5. If none of the conditions above are met, then the file is treated as a Calendar folder.

If a file is interpreted as a Calendar folder, the information in the file is imported into a new folder in the Outlook user's message store. If the file is interpreted as a Calendar object, it is presented to the user as a new item, which the user can then choose to save to their default Calendar folder.

When a webcal:// or webcals:// URL is opened, Outlook treats the file as a Calendar folder. A new folder is created for the first import of a particular URL, but subsequent imports of the same URL replace the contents of the folder created on the first import.

V0002:

The specification states that the charset, method, component, and optinfo parameters are optional.

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Parameter

Behavior

charset

This parameter is ignored on import. It is set to "utf-8" on export.

method

For both import and export, only the following values are supported: "REQUEST", "REPLY", "CANCEL", and "COUNTER" (case-insensitive). On import, if a "text/calendar" MIME part has a method parameter with any other value, or if the method parameter is not present, the MIME part is not imported as an iCalendar entity.

component

This parameter is ignored on import. It is not set on export.

optinfo

This parameter is ignored on import. It is not set on export.

V0004:

The specification states, "This [MIME content-type] can contain 8bit characters, so the use of quoted-printable or base64 MIME Content-Transfer-Encodings might be necessary when iCalendar objects are transferred across protocols restricted to the 7bit repertoire. Note that a text valued property in the content entity can also have content encoding of special characters using a BACKSLASH character escapement technique. This means that content values can end up encoded twice."

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Outlook can import "text/calendar" MIME parts that are encoded with base64 encoding. On export, Outlook does not use base64 encoding for "text/calendar" MIME parts.

V0006:

The specification states that the file extension ".ifb" is to be used to designate a file containing free or busy time information.

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Outlook does not export or import files with the ".ifb" file extension.

V0007:

The specification states that the Macintosh file type codes "iCal" and "iFBf" are to be used in Apple Macintosh operating system environments.

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Outlook does not install or operate in Apple Macintosh operating system environments. Consequently, it does not import or export files with the "iCal" or "iFBf" file type codes.