This is the first workflow, mostly technical,
where the information contained in the input data (Section 6.2) is treated and reformatted into the objects used by the downstream steps of the pipeline. The filters on the input data are also applied.
The astrometric information (AGIS coordinates, OGA3 and the Gaia Ephemeris) is used to associate to each sample of the spectrum the FoV coordinates of the source at the time when the sample crosses the CCD fiducial line, and a barycentric velocity correction is associated to each spectrum.