2.2.3.11 attOwner Attribute Handling by the TNEF Writer
If the message is either a meeting request or meeting cancellation (from the organizer, who is creating or deleting a meeting), the TNEF Writer SHOULD encode the PidTagSentRepresenting_XXX properties, as specified in section 2.1.3.1.1, in the attOwner attribute, as specified in section 2.1.3.3.16.
If the message is a meeting response of any type (from attendee, accepting, declining, and so on), the TNEF Writer SHOULD encode the PidTagReceivedRepresenting_XXX properties, as specified in section 2.1.3.1.1, in the attOwner attribute. The encoding used is implementation-dependent. For details about how to construct the EntryId property, see [MS-OXOMSG] section 2.2.1.25.
The TNEF Writer can use the discrete PidTag{Sent | Rcvd}Representing Name, AddressType, and EmailAddress properties if present, or access their values by using the PidTag{Sent | Rcvd}EntryId property.