At each point of the geodetic network kinematic quantities are considered: normal strain, shear strain and rotation. This differs from the treatment of deformations on the basis of point movements as the traditional geodetic approach. Strain and rotation depend on the changes of geodetic datum. In the case of two different coordinate systems in each epoch, we cannot ca/cu/ate the real value of movements, strains and rotations. Despite the empirical studies of the datum invariance, we derived analytical mathematical expressions of functional dependency of strains and rotations from the relative change of datum parameters between two measurement epochs. Practical demonstration of functional dependencies has been shown in the case of the selected planar geodetic network.