2.2.47 [RFC5545] Section 3.6.5, Time Zone Component
The specification describes the VTIMEZONE component.
Microsoft Office Outlook 2007, Microsoft Outlook 2010, Microsoft Outlook 2013
On import, Outlook attempts to approximate VTIMEZONE components to a VTIMEZONE with one annually-recurring standard-to-Daylight Saving transition date, and one annually-recurring Daylight Saving-to-standard transition date. The approximation process is specified in [MS-OXCICAL] section 188.8.131.52.1.19. Only the following properties are used to approximate a VTIMEZONE, all other properties are ignored: TZID (in VTIMEZONE components), DTSTART (in DAYLIGHT or STANDARD components), RRULE (in DAYLIGHT or STANDARD components), TZOFFSETFROM (in DAYLIGHT or STANDARD components), and TZOFFSETTO (in DAYLIGHT or STANDARD components). If a time zone cannot be approximated or parsed, it is ignored.