What is a shapefile? Relevant Environment Variables GrADS
version 2.0.a8 introduced the new capability to draw and query
the contents of a shapefile; version 2.0.a9 added the capability
to create new shapefiles from GrADS gridded or station data
sets. This documentation page serves as an overview of the GrADS
shapefile inteface, providing guidance on what shapefiles are,
how to find out what they contain, how to draw their contents,
and how to create new shapefiles. What is a Shapefile? The
shapefile format (promulgated by ESRI) stores non-topological
geometry and attribute information for the spatial features in a
data set. Shapefiles are used extensively in Geographic
Information Systems (GIS) and they typically contain data
related to coastlines, political boundaries, state or county
boundaries, climate zones, roads, rivers, topography, etc. The
geometry of each spatial feature or 'shape' is stored as a set
of vector coordinates. Shapes can be points, lines, or polygons
(areas). An ESRI shapefile actually