The standards and external programs supported by the QCI are using special Units of Measures. For example: The API 2004 needs the density in Kg/M3. But, it cannot detect the assignment of the unit name to the definition without making test calculations. Therefore the routine that calls that standard uses an internal description "DENSITY_KGM3" called QCI Unit. This logical unit must be assigned in the correspondent Conversion Group to any Unit of Measure that represents the density in Kg/M3, such as KGV.
So the QCI can make use of this assigned Unit of Measure to check and convert the input/output values.