https://learn.microsoft.com/cs-cz/dotnet/api/system.xml.serialization.xmlchoiceidentifierattribute.membername?view=netframework-4.8.1&viewFallbackFrom=netcore-1.1
XmlChoiceIdentifierAttribute.MemberName Property (System.Xml.Serialization) | Microsoft Learn
Gets or sets the name of the field that returns the enumeration to use when detecting types.
property systemxmlserializationmicrosoftlearn