https://learn.microsoft.com/en-us/dotnet/api/system.web.configuration.webconfigurationmanager.openmappedmachineconfiguration?view=netframework-4.8.1
WebConfigurationManager.OpenMappedMachineConfiguration Method (System.Web.Configuration) |...
Opens the machine-configuration file as a Configuration object to allow read or write operations.
system webmethodconfiguration