Memoptimize with RAW(16) datatype?

Good morning,

I am trying to test Memoptimize to know improvement using it, and for NUMBER primary key it works properly. I our last data model, primary keys are RAW(16) and it that case, it is not using memoptimize and make INDEX FULL SCAN instead of TABLE ACCESS BY INDEX ROWID READ OPTIM.

Could we use Memoptimize with RAW(16) datatype? Is only available for NUMBER primary keys? What kind of primary keys are enabled for it?

Thanks in advance for your help.

Regards,