using System;

class Program
{
    static void Main()
    {
        IsReferenceType<Enum>();
    }
    static void IsReferenceType<T>() where T : class
    {
        Console.WriteLine(typeof(T).IsClass); // False
    }
}

public abstract class Enum : ValueType, IComparable, IFormattable, IConvertible

Mab>public abstract class Enum : ValueType, IComparable, IFormattable, IConvertible
Mab>

Mab>

This property returns true for Type instances representing Enum and ValueType.

Console.WriteLine(typeof(Enum).IsClass); // false

using System;

class Program
{
    static void Main()
    {
        IsReferenceType<Enum>();
        IsReferenceType<ValueType>();
    }
    static void IsReferenceType<T>() where T : class
    {
        Console.WriteLine(typeof(T).IsValueType);
        Console.WriteLine(typeof(T).IsClass);
    }
}

False
False
False
True

N>using System;

N>class Program
N>{
N>    static void Main()
N>    {
N>        IsReferenceType<Enum>();
N>        IsReferenceType<ValueType>();
N>    }
N>    static void IsReferenceType<T>() where T : class
N>    {
N>        Console.WriteLine(typeof(T).IsValueType);
N>        Console.WriteLine(typeof(T).IsClass);
N>    }
N>}
N>

N>Во как! Он ни то, ни другое.

Remarks
<skipped>
This property returns true for enumerations, but not for the Enum type itself.

N>>Во как! Он ни то, ни другое.

AF>это еще не самое забавное

This property returns true for an enumeration, but not for the Enum type itself.