| Code | Category | Explanation |
|---|
| WS/W | Geod.Datum | Altitude datum / Lon Lat datum (W=WGS84, S=Mean Sea Level) |
| CCD | Method | CCD or CMOS imaging |
| PHG | Method | Photographic recording |
| PHM | Method | Photometer |
| VID | Method | Video recording |
| VIS | Method | Visual |
| WEB | Method | Webcam recording |
| B | Optics | Binoculars |
| E | Optics | Naked Eye |
| L | Optics | Lens optics |
| M | Optics | Mirror optics |
| GPS | Time Source | GPS receiver (no more info or only NMEA), unreliable method |
| GPS+ | Time Source | GPS NMEA with display correction applied |
| GPS++ | Time Source | GPS one Pulse Per Second |
| LAC | Time Source | Local atomic clock |
| NTP | Time Source | Network Time Protocol (no more info or Windows sys), unreliable method |
| NTP+ | Time Source | Permanent NTP synchro under Linux/Unix Sys |
| NTP++ | Time Source | Permanent NTP synchro with local atomic clock (observatories) |
| PHONE | Time Source | Phone time signal (wired phone) |
| RAD | Time Source | Radio time signal (no more info or intermittent radio control. clock) |
| RAD+ | Time Source | Intermittent radio controlled clock updated just before event |
| RAD++ | Time Source | Permanent radio time signal |
| TTV | Time Source | TV teletext display, unreliable method |