This indicates that the locomotive, train set or equipment is fitted with a decoder that has been pre-installed at the factory.
This means that the locomotive is ready to run and operate on a DCC controlled layout and can now be called up by request from a Digital Controller. Additional features, such as lighting and sound (if equipped), can also be independently controlled (only if the locomotive is fitted with these accessories).
Some DCC equipped locomotives can also be run on DC layouts (see note below). Some accessories may continue to work automatically, such as lighting and sound (if equipped), however, the user will not have independent control of these under DC operation. It is important to note that manufacturer's decoders who support sound playback on DC operation will only provide a selection of sounds when the locomotive is detected to be moving or stopping (such as chuffing, coasting and braking sounds).
*Some manufacturers may issue a warning that they do not recommend a DCC fitted locomotive to be operated on a DC (analog) layout, and may void any warranties. Check your locomotive's manual for more information. Not all sound decoders enable sound playback on DC operation, and this information is provided with your decoder manual.