You need to select one of the following usages (pikicube type="...") for a data series, which specifies the dimensions that are allowed to be used in the PIKI cube:
Regardless of the selected type of data series, process instance-independent measures are always of the PROCESS type, that is, they are handled like process measures.
The effects of the PIKI cube types are as follows.
PROCESS
Only process dimensions (dimtype="PROCESS" in the definition of the dimension) are allowed as referenced dimensions (refdim="...") in the data series.
OT_FUNC
Only process and function dimensions (dimtype="PROCESS" or "OT_FUNC" or "FUNCTION") are allowed as referenced dimensions in the data series.
RELATION (with relation name <x>)
Only process dimensions, relation dimensions of the relation <x>, and source and target dimensions of the relation <x> (that is, FPROCESSTYPE, FROMORG, TOORG, FUNCTION, ORGUNIT) are allowed as referenced dimensions of the data series.