How to represent an Enum in an Interface?

interface MyInterface
{
    void MyMethod(Enum @enum);
}

public enum MyEnum
{
  Hurr,
  Durr
}

public interface MyInterface
{
  void MyMethod(MyEnum value);
}

If this isn't what you're talking about doing, leave a comment so people can understand what your issue is. Because, while the enum isn't defined within the interface, this is a completely normal and acceptable design.