2.2.25 [RFC5545] Section 3.2.20, Value Data Types

V0033:

The specification describes the optional VALUE parameter.

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

On export, Outlook only exports the VALUE parameter for the following properties: ATTACH, EXDATE, RDATE, DTSTART, DTEND, and RECURRENCE-ID. For the ATTACH property, the value is either "BINARY" or absent. For the EXDATE, RDATE, DTSTART, DTEND, and RECURRENCE-ID properties, the value is either "DATE" or absent.

On import, Outlook ignores the VALUE parameter on all properties except for ATTACH. Furthermore, Outlook ignores any ATTACH properties that do not have one of the following combinations of the ENCODING and VALUE parameters: