Unlike the previous versions of the International Terrestrial Reference Frame (ITRF), the ITRF2005 is constructed with input data under the form of time series of station positions and Earth Orientation Parameters (EOPís). The ITRF2005 input time-series solutions are provided in a weekly sampling
by the IAG International Services of satellite techniques (the International GNSS Service-IGS, the International Laser Ranging Service-ILRS
and the International DORIS Service-IDS) and in a daily (VLBI session-wise) basis by the International VLBI Service (IVS).
Each per-technique time-series is already a combination, at a weekly basis, of the individual Analysis Center (AC) solutions of that technique,
except for DORIS.
Figure 1: ITRF2005 velocity field