CPP File Format
FileExtension .cpp is a generic identifier that indicates the contents contain pre-raPified text and can be raPified (binarised). This is by-convention-only. The actual contents could be binarised already. The engine doesn't care.
The binarised (raPified) equivalent of any .cpp file is .bin.
There are currently several cpp/bin files used by bis.
In all circumstances, a .cpp, if present in the same folder, takes precedence. (the .bin is ignored).