an output control apparatus is interposed between a host computer for generating data and a printer , and controls the printer . the control apparatus includes a plurality of data generators , a discriminator , a controller and a notifying device . the data generators interpret a plurality of printer languages and perform control processing . the discriminator analyzes received data and specifies by which of the plurality of data generators control based upon the received data is to be carried out . the controller , in a case where one data generator is not specified by the discriminator and an error resulting from interpretation failure occurs during the course of processing by one data generator selected under prescribed conditions , causes the discriminator to re - execute processing based upon data in which the interpretation failure occurred . the notifying device notifies of a request for re - transmission of data in a case where one of the data generators is specified anew by the controller .