ManagePolygons(polys = NULL, poly.data = NULL, poly.crop = NULL,
encoding = getOption("encoding"), parent = NULL)gpc.poly-class."latin1" or "UTF-8" it is used to mark character
strings as known to be in Latin-1 or UTF-8: it is not used to re-encode
the input.polys, poly.data, and poly.crop
(see read.polyfile within the polyfile, union, setdiff,
intersect