AnonymousDataMember or AnonymousDataMemberAttribute identifies
a DataMember, which is declared as an 'object', but which at runtime
can contain instances of various unknown types.
Here you cannot serialize directly via [DataContract] and [DataMember].
The data must be processed separately.
Naturally, many findings and developments are based on information freely available on the Internet. Any missing references to original authors are unintentional and will be updated as soon as they are reported.