Visual Dorp Filter ( VDF ) or Object Oriented Filtering (OOF) Vdf objects are set of date-centric filtering objects and provided to help speed the process of filtering application development. Because of large amount of data records that could be received in visual systems, there is a problem of selection / filtration for asked data. For that purpose the basic objects (classes) have been developed to make filter forms, in order to work with Visual FoxPro and SQL.