Enum Class Default Initialization

Is the default initialization/construction of enum classes defined behavior?

Here is a minimal example(Try Online)

enum class ALPHA{
    X = 0,
    Y = 1,
    Z = 2,
};

int main()
{
    ALPHA a = ALPHA(); // use default constructor
    ALPHA b{}; // use default initialization
    std::cout <<static_cast<int>(a) << std::endl; // 0
    std::cout <<static_cast<int>(b) << std::endl; // 0
    return 0;
}

I get zero in both cases. So does the default initialization pick the first enum type(eg. here X = 0) always? I know that it is UB for standard enums but Im not sure about the semantics for enum classes? I looked this up on CPPReference too but didnt find any relevant information about it - Is it possible to get a standard reference too?