-BNS requires GNSS clocks and orbits in the IGS Earth-Centered-Earth-Fixed (ECEF) reference system in SP3 format. They can be provided by a real-time GNSS engine such as RTNet. In contrast to SP3 the required clocks have to be corrected for relativistic effects, namely the 2nd-order periodic time correction -2(R * V)c^2. +BNS requires GNSS clocks and orbits in the IGS Earth-Centered-Earth-Fixed (ECEF) reference system in SP3 format. They can be provided by a real-time GNSS engine such as RTNet. In contrast to SP3, the incoming clocks must have been corrected for the 2nd-order relativistic effect. This is a priodic time correction defined as -2 (R * V) / c^2 and includes the scalar product of satallite position and velocity divided by the speed of light raised to the second power.