https://learn.microsoft.com/en-us/dotnet/api/system.xml.serialization.xmlanyelementattributes.system-collections-ilist-item?view=dotnet-uwp-10.0&viewFallbackFrom=net-10.0
XmlAnyElementAttributes.IList.Item[Int32] Property (System.Xml.Serialization) | Microsoft Learn
Gets or sets the element at the specified index.
property systemilistitemxmlserialization
https://learn.microsoft.com/en-us/dotnet/api/system.xml.serialization.xmlanyelementattributes.system-collections-ilist-add?view=dotnet-uwp-10.0&viewFallbackFrom=net-10.0
XmlAnyElementAttributes.IList.Add(Object) Method (System.Xml.Serialization) | Microsoft Learn
Adds an item to the IList.
ilistaddobjectmethodsystem