When assigning an Evaluation rule to a component A of a component Y of a non-transparent field X, the component Y is considered as a determination object. If there is a rule assigned to Y in table CNV_10020_RDTOBJ, it is assigned to X-Y instead of Y. This happens also to the parameters Pi that are stored as X-Pi. Set the indicator if you want keep the parameter on top level Pi.
Example
There is an evaluation rule AWORG_BUKRS assigned to to component BUKRS of determination object AWORG. The rule requires a parameter AWTYP. The field AWKEY consists of the two components AWORG and AWREF. When assigning a rule to the component BUKRS of AWKEY-AWORG, the parameter AWTYP is assumed to be in AWKEY as well (just one level deeper). Actually, it is not. There has to be a search for it on top level.