According to the new structure of IERS implemented in 2001 three ITRS Combination Centres are responsible for the computation of ITRS realizations. After a validation procedure, one realization is defined to be the official ITRF solution.
For the ITRF2008, IGN and DGFI-TUM contributed by computing ITRS realizations. The realization computed by IGN was selected as the official ITRF2008.
For the ITRF2014, IGN, DGFI-TUM, and JPL contributed with their respective ITRS realizations. The realization computed by IGN was selected as the official ITRF2014.
For the ITRF2020, IGN, DGFI-TUM, and JPL contributed ITRS realizations. The realization computed by IGN was selected as the official ITRF2020.
For the ITRF2020,updates were provided by IGN, DGFI-TUM, and JPL: IGN released ITRF2020-u2023 and ITRF2020-u2024, DGFI-TUM released DTRF2020-u2023, and JPL released JTRF2020-u2022.
