标题：Geodetic Datum and No Net Translation (NNT) - No Net Rotation (NNR) Conditions from Transformation Parameters, a Reference Frame and a Selection Matrix
摘要：The definition of the geodetic datum is a fundamental issue in the solution of the inverse problems related with the adjustment of free geodetic networks. Taking into account the conventions given by the International Earth Rotation and Reference System Service (IERS) on the definition and realization of a Terrestrial Reference System (TRS), it is considered here that a geodetic datum is the set of all conventions, algorithms and constants necessaries to define and realize the origin, orientation, scale and their time evolution of a TRS in such a way that these attributes be accessible to the users through occupation, direct or indirect observation.
