This module contains tools for accessing spatial reference databases. These
are databases (either local or remote) from which you can look up
coordinate system specifications, typically in either OGC or Proj4 format. For example, you can access the
spatial_ref_sys table provided with an OGC-compliant RDBMS
such as PostGIS. You can also read the database files provided with the
proj4 library, or access online databases such as the spatialreference.org
site.