The purpose of this Recommendation is to establish common conventional algorithms and procedures to be used in comparing clocks on the surface of the Earth and on platforms far from the Earth but within the solar system. These expressions are explicitly determined in the general relativity theory that is presently accepted to form the basis of space-time reference systems. It is envisioned that these algorithms and procedures would be used for comparisons of clocks on Earth satellites, interplanetary spacecraft, and on the surfaces of solar system bodies.
ITU-R TF.2018-2012 history
2012ITU-R TF.2018-2012 Relativistic time transfer in the vicinity of the Earth and in the solar system