DLG (Digital Line Graphs)

http://www.dnr.sc.gov/GIS/img/beaufdlg.gif

A DLG, often used by the U.S. Geological Survey, is a digital vector representation of information. A DLG can show information such as boundaries, borders, roads, and other data represented by lines, curves, and other shapes. This DLG shows different boundaries, borders, and the hydrography of a specific area.