To date, there are numerous variants of designated verifier signatures(DVS), including the notion of strong DVS, multi DVS, universal DVS, etc. Inthis paper, for the first time, we present a generic definition of DVS model. Wealso explore the related security notions in DVS, including unforgeability, nontransferabilityand non-delegatability, and study the relationship of these notionsagainst variants of DVS. Furthermore, we classify the multi designated verifiersignature schemes into four categories depending on the way the verification andsimulation is performed. We also point out some drawbacks on the existing DVSschemes, and finally present a new and efficient constant size multi DVS schemethat produces a constant size signature regardless the size of the receivers group.Our scheme is proven secure in the standard model.