The data file is merely a character string which
specifies the name of an environment variable which contains the
base location of the binary files used by the map drawing functions.
This environment variable (R_MAP_DATA_DIR
for the datasets in the
maps package) is set at package load time if it does not
already exist. Hence setting the environment variable before loading
the package can override the default location of the binary datasets.
During a transition period (maps
version 3.0) it is possible to switch to the old legacy map using the function world.legacy(TRUE)
or by setting the setting the environment variable R_MAP_DATA_LEGACY=TRUE prior to loading the package.
In future releases, this dataset will be removed completely. It will however remain accessible via the mapdata
package (as of version 2.3.0), where it is called worldLores