In all DACs, the output is the product of the reference voltage and the digital code.  So in a sense, all DACs are multiplying DACs, but many DACs operate well only over a limited range of Vref. True Multiplying DACs (MDACs), however, are designed to operate over a wide range of Vref. A strict definition of an MDAC demands that its reference voltage range include 0V. However, many, especially current mode ladder networks with CMOS switches, permit positive, negative and AC Vref. DACs which do not work down to 0 V Vref are still useful. Types where Vref can vary by 5:1 or so are often called MDACs, although a more accurate description might be "semi-multiplying" DACs.