With Validation on demand a user can upload his own reference databases via internet so that client data, in batch or transactional, can be matched with this reference database. The user will acquire an overview of client data that is already in the system; client data that is definitely not in the system and client data for which it is uncertain. In this case of doubt, it can be quickly determined in a (semi) automated way, whether the client data is in the reference file or not.