| Range | Set by: | Reserved for: |
| 0-9.xxx | detcom | FITS structure keywords (must be in order) |
| 5x.xxx | detcom | Summary, ID and observer comment strings |
| 7x.xxx | detcom | General (filename, dates, acquisition configuration) |
| 1xx.xxx | detcom | Detector (size, binning, pixel scale) |
| 3xx.xxx | detcom | World Coordinate System |
| 5xx.xxx | tcs | Telescope (RA/DEC, bonnette, guider) |
| 7xx.xxx | aob | Adaptive Optics |
| 9xx.xxx | Calibration sources | |
| 1xxx.xxx | detcom,fipcom, fperoth,mosh sish,geckoh? | Instrument (Filter, shutter, wheel) |
| 4xxx.xxx | fperoth,mosh,sish,geckoh | Spectrograph (grism, ???) |
| 9xxx.xxx | logger | Environment (probe measurements, plant monitoring) |
| 20xxx.xxx | qso | Queue Scheduled Observing system |
| 40xxx.xxx | elixir | Processing pipeline |
| 99xxx.xxx | newdatah | Archive system |