At some point of history it was decided that the prefixed unit kg should be SI unit for mass. (Not saying that this was a logical choice. Maybe otherwise it might have been too similar to cgs?)
UBASE aka BASE in Unit menu returns g instead of kg (e.g. trying 1_Pa UBASE), which is also not inline to user manual of HP 48.
At some point of history it was decided that the prefixed unit kg should be SI unit for mass. (Not saying that this was a logical choice. Maybe otherwise it might have been too similar to cgs?)
UBASEakaBASEin Unit menu returns g instead of kg (e.g. trying1_Pa UBASE), which is also not inline to user manual of HP 48.