Another useful info is probably that internally the engine stores enums as 8-byte unsigned integers. Hence why in C++ the standard namespace enum is deprecated (as far UE4 is concerned)
The norm in UE4 is this:
UENUM(BlueprintType)
enum class EMyEnum : uint8
{
OPTION_A UMETA(DisplayName = "Option A"),
OPTION_B UMETA(DisplayName = "Option B"),
MAX UMETA(Hidden)
}