https://wiki.freepascal.org/Platform_defines#Operating_system_defines I 've added all defines of OS. You can tell me if it's not ok. Missed one item: 'nativent' target. Seems some Win32 target? why new? Why it don't have extradefines "windows"? https://github.com/graemeg/freepascal/blob/master/compiler/systems/i_nativent.pas -- Regards, Alexey