You don't start or stop a file with anything, unless MP3 needs some sort of header information. But that is out of the scope of the FAT32 filesystem.

You will need to create a directory entry and use the File Allocation Table (FAT) to allocate one or more clusters to store your data into. The hardest part of the FAT32 filesystem is dealing with Long Filenames in the directory.

Do a google search for... "FAT32 Structure" and you get gobs of information.

<>< Lance.