The Digital Chart of the World (DCW) is a comprehensive 1:1,000,000
scale vector basemap of the world. The charts were designed to meet
the needs of pilots and air crews in medium-and low-altitude
en route navigation and to support military operational planning,
intelligence briefings, and other needs. DCW-GMT is an enhancement
to DCW in a few ways: (1) it contains more state boundaries,
and (2) the data have been reformatted to save space and are
distributed as a single deflated netCDF-4 file.