For Gaia DR2, no standard selection was carried out for the photometric processing of the fluxes. This was because there was no pressing need to reduce the number of transits or
sources entering the calibrations and that there were robust procedures, e.g., sigma clipping, within the calibrations to deal with non-constant sources and outliers.
Additionally, at the bright end, due to the small-scale calibration being very complex,
it was necessary to maximise the number of transits
available entering the calibrations by using all sources. In future data releases, it is
intended to use a transit selection procedure to reduce the number of observations used by the calibrations in order to reduce the memory footprint and speed up the iterations.