The Xbox 360 system uses a series of bootloaders to load the hv/kernel and dashboard. These loaders are explained at Boot Process.
The header is at the start of the bootloader and is usually 0x20 bytes long.
| Offset | Length | Type | Information |
|---|---|---|---|
| 0x0 | 0x2 | ASCII characters | Loader name |
| 0x2 | 0x2 | unsigned short | Loader build number |
| 0x4 | 0x2 | unsigned short | Loader pairing data |
| 0x6 | 0x2 | unsigned short | Loader flags |
| 0x8 | 0x4 | unsigned integer | Loader entrypoint |
| 0xC | 0x4 | unsigned integer | Loader length (including header) |
| 0x10 | 0x10 | bytes | HMAC salt (used for decrypting the loader) |