DLG

http://tahoe.usgs.gov/DLG.html

This is an example of a DLG. A DLG or Digital Line Graph is a digital representation of the features displayed on a U.S. Geological Survey topographic map.  DLGs contain a wide variety of information depicting geographic features. Example: hypsography, hydrography, boundaries, roads, utility lines, etc
The map above is a DLG of Lake Tahoe