| Code figure | Meaning |
| 0 | Grid point data - simple packing |
| 1 | Matrix value - simple packing |
| 2 | Grid point data - complex packing |
| 3 | Grid point data - complex packing and spatial differencing |
| 4-49 | Reserved |
| 50 | Spectral data - simple packing |
| 51 | Spherical harmonics data - complex packing |
| 52-191 | Reserved |
| 192-254 | Reserved for local use |
| 255 | Missing |