| Octet No. | Contents |
| 1-4 | "GRIB" (coded according to the International Alphabet No. 5) |
| 5-6 | Reserved |
| 7 | Discipline - GRIB Master Table Number (see Code Table 0.0) |
| 8 | GRIB edition number (currently 2) |
| 9-16 | Total length of GRIB message in octets (including Section 0) |