| Category | Description |
| 0 | Temperature |
| 1 | Moisture |
| 2 | Momentum |
| 3 | Mass |
| 4 | Short-wave radiation |
| 5 | Long-wave radiation |
| 6 | Cloud |
| 7 | Thermodynamic stability indices |
| 8 | Kinematic stability indices |
| 9 | Temperature probabilities |
| 10 | Moisture probabilities |
| 11 | Momentum probabilities |
| 12 | Mass probabilities |
| 13 | Aerosols |
| 14 | Trace gases (e.g. - ozone, CO2) |
| 15 | Radar |
| 16 | Forecast radar imagery |
| 17 | Electro-dynamics |
| 18 | Nuclear/radiology |
| 19 | Physical atmospheric properties |
| 20-189 | Reserved |
| 190 | CCITT IA5 string |
| 191 | Miscellaneous |
| 192-254 | Reserved for local use |
| 255 | Missing |