List of British Rail departmental multiple unit classes
The 900 series classes were reserved for multiple units in departmental stock, most of which were converted from old passenger units. In broad terms, classes 930-935 were allocated to Southern Region multiple units (ex-200 and 400 series), 936 & 937 to other EMUs (ex-300 and 500 series) and 960 to other DMUs (ex-100 series). In recent years, this has been less rigidly adhered to.