WindowsTextFiles have an interesting property. They end whenever the character "\x1A" is encountered. You can add this character and then the header that PodMaster hinted at. I would add the offset of the "\x1A" at the very end of the file to see if someone has edited the file without regard for your header or if it is newly generated and doesn't contain a header yet. BTW the access to the last part of a file is slow on all FAT-filesystems.