Optical devices use slots on a shelf to place optical equipment. Depending on the equipment and the supplier, some devices span multiple slots while some suppliers place multiple equipments within a single slot. The latter case is referred as subslot or subcard handling. Optical Transport Management Suite supports explicit subcard modeling capability. Both cards and subcards are modeled as OTM class "Card" in the OTM topology. Figure 25 depicts a subslot configuration.