<PackageReference Include="System.Configuration.ConfigurationManager" Version="4.6.0-preview5.19224.8" />

OverrideMode

public enum OverrideMode
Specifies the override behavior of a configuration element for configuration elements in child directories.
Allow = 1

The configuration setting of the element or group can be overridden by configuration settings that are in child directories.

Deny = 2

The configuration setting of the element or group cannot be overridden by configuration settings that are in child directories.

Inherit = 0

The configuration setting of the element or group will be overridden by configuration settings that are in child directories if explicitly allowed by a parent element of the current configuration element or group. Permission to override is specified by using the OverrideMode attribute.