2.2.5 [RFC5545] Section 3.2, Property Parameters

C0001:

The specification defines a set of parameters but does not specify how to respond to undefined or unrecognized parameters.

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

On import, Outlook ignores any parameters that are undefined or unrecognized. It also ignores recognized parameters in unsupported contexts (for example, a FMTTYPE parameter on an ATTENDEE property).

On export, Outlook exports some xparams, as specified in [MS-OXCICAL].