The dimension values are enabled for the dimension search differently, depending on the type of the dimension search that you use.
Default dimension search.
All dimensions are always enabled for the default dimension search. That is, all dimensions are searched by the MDEX Engine in the default dimension search.
Unlike record search (which is disabled by default and therefore must be configured), there are no special configuration settings necessary to enable all dimensions for the default dimension search.
Compound dimension search.
If you use the --compoundDimSearch flag for Dgidx, all dimensions are enabled for the compound dimension search, that is they are searched by the MDEX Engine in the compound dimension search.
Java: setDimSearchCompound() method
.NET: DimSearchCompound property