I can do this

const uint    X    =    1;

enum E
{
    Z = X
}

but not this

const uint    X    =    1;
const uint    Y    =    X;

enum E
{
    Z = Y
}

or this

const uint    X    =    1;
const uint    Y    =    X;

enum E : uint
{
    Z = Y
}