Both Default and NotSet are documented as:

> This is the default behavior.

Please explain how and what circumstance each one is the default behavior.

I am going to guess that Default is the default value set by code somewhere. It would also seem that NotSet is documented as default because it’s what you get from this C# expression: default(FcnMode) or for any uninitialized field.

Document Details

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• ID: 75aff974-f324-1fb1-d9bb-fce579f1db80
• Version Independent ID: ebc004a9-bc4a-b147-7e3e-7f650f51d6f9
• Content: FcnMode Enum (System.Web.Configuration)
• Content Source: xml/System.Web.Configuration/FcnMode.xml
• Product: dotnet-api
• GitHub Login: @dotnet-bot
• Microsoft Alias: riande