This is a list of locomotives and multiple unit classes of the DSB, the primary train operator in Denmark. Steam locomotive classes were usually designated by a single capital letter, whereas diesel locomotives and DMUs are named with two (occasionally, three) letters, the first being an M for "motor"; electric locomotives and EMUs are given two-letter combinations, the first being an E. The classes are referred to as "litra" (from Latin littera, "letter") in Danish, e.g. "litra MY" for the class MY locomotives. In addition to this class designation, each locomotive or multiple unit within a class has its own number.