++++ 1. Officials ° Assignment ° Re-assignment under a staff rotation system ° Distinguished from the filling of a vacant post ° Administration' s obligations to comply with the principles of equal treatment and the protection of legitimate expectations (Staff Regulations, Arts 4, 29 and 45) 2. Officials ° Assignment ° Re-assignment under a staff rotation system ° Administration obliged to select one of the officials who has submitted an application ° No such obligation