The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Vehicle (8 members)
- Hecto (0 members)
- GeothermalHeatTransfer (0 members)
- MassUnit (20 members)
- SubsurfaceCollector (0 members)
- SurfaceAzimuthAngle (0 members)
- ElectricityCost (0 members)
- SectorDivision (5 members)
- SolarElectricalEnergy (0 members)
- TestOntologyClassA12 (0 members)
- IlluminanceUnit (2 members)
- CarbonCaptureAndStorage (0 members)
- MillionTonOfOilEquivalent (0 members)
- NewtonPerMeter (0 members)
- MyDataset (1 member)
- Microvolt (0 members)
- CompressedSyntheticMethane (0 members)
- BigMapBatteryCell (3 members)
- ArealEnergyDensityUnit (0 members)
- SolarReceivingObject (8 members)
- Millimole (0 members)
- DimensionMeasuringDevice (0 members)
- CompressedAirEnergyStorageUnit (1 member)
- TensileTestInAccordanceWithIso68921 (0 members)
- ConcentrationUnit (18 members)
- FrequencyControl (3 members)
- MolarVolumeUnit (2 members)
- Symbol (2 members)
- Animal (1 member)
- Plotting (0 members)
- Train (2 members)
- Api (0 members)
- Milliampere (0 members)
- StudyReport (0 members)
- Model (6 members)
- SquareAngstrom (0 members)
- EuEmissionSectorDivision (0 members)
- Prüfkörper (0 members)
- TemperatureChangeDevice (0 members)
- Ampere (0 members)
- City (0 members)
- SensibleSolidHeatStorageObject (0 members)
- EnzymeUnit (0 members)
- Propulsion (1 member)
- CodeSource (0 members)
- HardCoal (2 members)
- Port (2 members)
- FuelTransport (1 member)
- RunOfRiverPowerPlant (0 members)
- ModellingSoftware (0 members)