| CentimeterGramUnitSystem | 2 | Specifies centimeters as the default distance units and grams as the default mass units of the design. | 
      
        | CustomUnitSystem | 0 | A custom unit system that supports any combination of distance and mass units as the default units of the design. | 
      
        | FootPoundUnitSystem | 5 | Specifies feet as the default distance units and pounds as the default mass units of the design. | 
      
        | InchOunceUnitSystem | 4 | Specifies inches as the default distance units and ounces as the default mass units of the design. | 
      
        | MeterKilogramUnitSystem | 3 | Specifies meters as the default distance units and kilograms as the default mass units of the design. | 
      
        | MillimeterGramUnitSystem | 1 | Specifies millimeters as the default distance units and grams as the default mass units of the design. |