Correct, as I understand it, Add Ins must be, and always are, in one of those two locations. But, this isn't a mac limitation/difference. As I understand it, Windows may let you drag a .def file into JMP, but what happens then is jmp copies that over to the Windows location for JMP Add Ins, of which there is also a user-specific, and global location. I suspect on a drag into jmp, the file would be ported over to the user roaming location: C:\Users\<USER>\AppData\Roaming\SAS\JMP\Addin
@julian