2.2.55 [RFC5545] Section 3.8.1.2, Categories

V0091:

The specification states that non-standard and language property parameters can be specified on the CATEGORIES property.

Microsoft Office Outlook 2007, Microsoft Outlook 2010, Microsoft Outlook 2013, Microsoft Outlook 2016, Microsoft Outlook 2019

Outlook does not export non-standard or language property parameters on the CATEGORIES property, and ignores all parameters on the CATEGORIES property on import.

V0092:

The specification states that the CATEGORIES property can be specified within the VEVENT, VTODO, or VJOURNAL components.

Office Outlook 2007, Outlook 2010, Outlook 2013, Outlook 2016, Outlook 2019

Outlook only exports the CATEGORIES property within VEVENT components. On import, CATEGORIES properties in any component other than a VEVENT component are ignored.

V0093:

The specification states that multiple categories can be specified as a list of categories separated by the COMMA character (US-ASCII decimal 44).

Office Outlook 2007, Outlook 2010, Outlook 2013, Outlook 2016, Outlook 2019

On export, Outlook exports at most one CATEGORIES property per VEVENT component. The value of the CATEGORIES property can contain multiple categories, which are separated by commas.

On import, Outlook can parse multiple instances of the CATEGORIES property on a single VEVENT component. When parsing the list of categories, Outlook applies additional rules to the values, including truncation of whitespace and removal of duplicates. These additional rules are specified in [MS-OXCICAL] section 2.1.3.1.1.20.3.