Grammar for 3GF files The file is structured in fixed sets of 10 bytes. The 2 bytes are used as a 16bit signed integer. Bytes 0-1: Always 00 00 Bytes 2-3: The time offset in milliseconds Bytes 4-5: Vertical acceleration with 128 equaling 1g Bytes 6-7: Horizontal acceleration Left-Right with Right being positive Bytes 8-9: horizontal acceleration Forward to Back with Back being positive