AP7 – 100 – The propagation mode (1) required distance is then the maximum distance in the series of propagation mode (1) distances that are obtained for any value of pn, subject to the constraint associated with equation (123). A detailed description of the method for using equation (123) to determine the propagation mode (1) required distance is provided in § 4.2. Further information, including examples, may be found in the most recent version of Recommendation ITU-R SM.1448. ANNEX 7 System parameters and predetermined coordination distances for determination of the coordination area around an earth station 3 Horizon antenna gain for a receiving earth station with respect to a transmitting earth station