There are two script compilers around.
Heinz's compiler (ipp.exe) is most widely used, but it has several "features", that might be fixed soon.
The second (actually, first) is the original Interplay's compiler . This native Fallout compiler is not accessible (as far as I know), but one can grab its modification for Klingon Academy game. Both games have the same scripting engine (the same subset of system opcodes), so if you need to play with completely correct script compiler - this is the best choice.