https://learn.microsoft.com/en-us/dotnet/api/system.messaging.binarymessageformatter.topobjectformat?view=netframework-4.8.1
BinaryMessageFormatter.TopObjectFormat Property (System.Messaging) | Microsoft Learn
Gets or sets a value that defines how the top (root) object of a graph is deserialized with regards to finding and loading its assembly.
property systemmessagingmicrosoftlearn