Hello dave
In my programm i have this:

INCLUDE "modedefs.bas"
INCLUDE "DT_INTS-18.bas"
INCLUDE "ReEnterPBP-18.bas"

ASM
INT_LIST macro
INT_Handler RX_INT, _IntRx, PBP, yes
endm
INT_CREATE
ENDASM
@ INT_ENABLE RX_INT

Best regards
Pedro