Just a small note (maybe it helps someone).
Typically, some exports are done using XML.
That XML it typically generated using a simple POCO.
When migrating to a new version, you will still want to support older versions, but signal developers that the field is no longer in use for new data.
Whatever you do, don’t make the field Obsolete.
Making it Obsolete makes it no longer deserialize from the XML source.
I found out the hard way today 🙂