Base unit and System unit in Microsoft Dynamics 365 for Supply Chain Management

Base unit

Helpful in unit conversions without need to define all conversions to and from with this unit and other units in same unit class

System unit

Unit of measure that is applied when a measurement or quantity is entered in fields in Microsoft Dynamics 365 for Supply Chain Management that are not associated with a specific unit of measure.

D365FO uses this when no UOM is specified /can be specified on a form e.g. when only a qty field is present, D365FO uses system unit to interpret the qty