C# Language Specification

The System.Enum type

The type System.Enum is the abstract base class of all enum types (this is distinct and different from the underlying type of the enum type), and the members inherited from System.Enum are available in any enum type. A boxing conversion (§4.3.1) exists from any enum type to System.Enum, and an unboxing conversion (§4.3.2) exists from System.Enum to any enum type.

Note that System.Enum is not itself an enum-type. Rather, it is a class-type from which all enum-types are derived. The type System.Enum inherits from the type System.ValueType (§4.1.1), which, in turn, inherits from type object. At run-time, a value of type System.Enum can be null or a reference to a boxed value of any enum type.

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