A unit system may be optionally specified during AIM instance initiation. If a unit system is provided, all AIM input values which have associated units must be specified as well. If no unit system is used, AIM inputs, which otherwise would require units, will be assumed unit consistent. A unit system may be specified as "SI" or "US", which corresponds to the SYSTEM_MEASUREMENTS keyword in the configuration file. See SU2 template for additional details.