This is a Vector data set. The map projection used is Lambert Conformal Conic. The horizontal datum used is NAD27. The semi-major axis of the ellipsoid used is 6378206.4 meters. There are no user-defined polygon attributes.
Values are in decimal degrees.
Q75 - Indicates if arc is a boundary for a 7.5 minute quad. Q100BASE - Defines 30x60 min. Q250BASE - Defines 1 x 2 degree quadrangle boundaries for cartographic use. These boundaries differ significantly from the typical rectangular quadrangle shape. This data set was created to serve as base map information.