Daily Effective Circulation (DEC): A potential exposure of an advertising display. DEC represents the average number of potential viewers over a 12-hour period for regular panels, or 18 hours for illuminated structures.

Day-Glo: Trade-name for some inks or lacquers that become fluorescent when activated by ultraviolet rays of sunlight or special illumination.

Demographic profile: Audience breakdown based on individual characteristics such as sex, age, income or education.

Department of transportation (DOT): Official agency of the federal, state or city governments that regulate and studies traffic flow, and issues statistical data. DOT studies form the basis of most DECís audits by the TAB.

Digital printing: High resolution, computer-controlled inkjet printing that produces high quality images in virtually any size. Digital printing has become the most common form of printing for outdoor media.

Diorama: A backlit display located in airports, bus terminals, malls and sport stadiums/arenas.

Display period: The length of time in days that an individual advertising message is on display.

Distribution: Location of outdoor media structures within a given market, relative to exposure potential.

DMA (Designated Market Area): A rigidly defined market area used to identify a media market. Non-overlapping DMAs cover the entire country.