The Gaia data processing makes use of a large number of constants and parameters. These vary from mathematical constants, through constants of nature, to parameters describing the instrument (for instance the number of CCD rows). To keep track of constants and parameters in a controlled way, all data processing software interfaces to the Gaia Parameter Data Base (Section 1.2.3; Perryman et al.2008). This data base is updated regularly (under configuration control) and is based on industrial design documents and other sources of information. Gaia data releases use IAU resolutions up to and including 2012, the 2010 version of the CODATA recommended values of the fundamental physical constants (Mohr et al.2012), and the INPOP10e solar-system ephemerides (Section 3.2.1; Fienga et al.2016, 2011).