Detailed information on classification method is available at Torres et al 2019.
This is part of The SVO archive of White Dwarfs from Gaia
The SVO archive of White Dwarfs from Gaia is the result of a joint collaboration between the Centro de Astrobiología (CAB, CSIC-INTA) and the Universitat Politècnica de Catalunya (UPC). It has been developed in the framework of the Spanish Virtual Observatory project supported by the Spanish MINECO through grant AYA 2017-84089 and ASTERICS, a project supported by the European Commission Framework Programme Horizon 2020 Research and Innovation action under grant agreement n. 653477. The system is maintained by the Data Archive Unit of the CAB (CSIC -INTA).
If you use this service in your research, please cite Torres et al 2019 and include the following acknowledgement in any resulting publications: "Based on data from the SVO archive of White Dwarfs from Gaia at CAB (INTA-CSIC)".