https://learn.microsoft.com/en-us/dotnet/api/system.data.common.datatablemappingcollection.indexof?view=netframework-4.8.1&viewFallbackFrom=net-10.0
DataTableMappingCollection.IndexOf Method (System.Data.Common) | Microsoft Learn
Gets the location of the specified DataTableMapping object within the collection.
system dataindexofmethodcommonmicrosoft