This is a mathematically generated grid in which each polygon represents one quarter of the already quartered 225 second (or 3 3/4 minute) data resource, or a quarter-quarter of a standard USGS 7 1/2 minute quadrangle. The result is a 1 7/8 minute quadrangle layer which nests within the standard USGS quads and whose tile naming scheme includes reference to the parent quadrangles. Known as the "Quarter-Quarter Quad" tile index.
To provide a standard framework for accessing and creating data sets tiled by "quarter-quarter-quad." Especially for use with collecting, organizing, and distributing LiDAR data and derived products.
Processing occurred in 2001.