https://learn.microsoft.com/en-us/openspecs/exchange_server_protocols/ms-oxwsatt/7f696837-53f6-46ce-9b4d-00acad4ad103?redirectedfrom=MSDN
[MS-OXWSATT]: t:AttachmentType Complex Type | Microsoft Learn
The AttachmentType complex type represents an attachment.
complex typemsmicrosoftlearn