Enables compatibility mode. 3DS and Wii U exclusive features can't be used. These are:
3DS Multiplayer (MPSTART,MPGET,MPNAME$,MPRECV,MPSEND,MPSET,MPSTAT)
(Unknown SB BIG features)
Compatibility mode is ended automatically when a program ends, unlike other XON options.
Disables compatibility mode.
XON 3DS and XON WIIU
These do the same thing as XOFF COMPAT, but only work on their respective systems. Using XON WIIU will cause an error on the 3DS version, and XON 3DS will cause an error in SmileBASIC BIG.
(I'm not sure if all this is entirely correct since I can't test the Wii U version)