-When using clocks from Broadcast Ephemeris (with or without corrections) and clocks from SP3 files in the same application, it is important to understand that Broadcast Ephemeris clocks - according to the Interface Control Documents (ICD) - are corrected for the 2nd-order relativistic effect whereas clocks from SP3 files are not. The 2nd-order relativistic effect 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. +When using clocks from Broadcast Ephemeris (with or without applied corrections) or clocks from SP3 files, it may be important to understand that they are not corrected for the 2nd-order relativistic effect. The 2nd-order relativistic effect 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.