According to Rambam, the Explicit Name of God is either the Tetragrammaton or the Name Ado-nai. According to Ramah and Ritva, Y-H-V-H is referred to as the Explicit Name, but not Ado-nai. But it is possible that for Gentiles, they agree that Ado-nai is also considered an Explicit Name, and that Gentiles are liable for cursing it, just as for cursing the Name Y-H-V-H.