To add to what ColJack said, the batch file (usually called p.bat) will run your script through the compiler's preprocessor, in order to expand any macros in the script. After that, the script will be compiled with the script compiler that comes with the mapper.
Anyways, this is already covered in the mapper readme and in ColJack's tutorial, so next time, try reading the friendly manual before posting. It will save you (not to mention us) a lot of time.
Anyways, this is already covered in the mapper readme and in ColJack's tutorial, so next time, try reading the friendly manual before posting. It will save you (not to mention us) a lot of time.