Data flow of FRIEND represented, from left to right, as the six steps explained in the text. There are the different raw data (grey boxes), the products of calibration (green boxes), the quality controls (brown boxes), and the products of the processing (orange boxes). Some products are required to proceed to the enxt step (red circles). Different selections are made on the raw frames (Sorting boxes): Sorting 1 removes the frames with flashes and Sorting 2 removes frames on photometric criteria.