 The DP70 was Philips's original model name for the projector, and this is what projectionists in Europe tend to call it.In the United States, the American Optical Company (the AO in Todd-AO) used the Philips factory model number, EL4000/01 (the 60 Hz variant – the 50 Hz one, for sale in European markets, was model no.EL4000/00), as their catalog number for the machine.