One location on the globe, in any coordinate system. Geo::Point is a Perl module that tries to hide the maths and the coordinate system in which the point is represented.
One of the most confusing things when handling geometrical data, is that sometimes latlong, sometimes xy are used: horizontal and vertical organization reversed. This packages tries to hide this from your program by providing abstract accessors latlong(), longlat(), xy(), and yx().
my $p = Geo::Point->latlong(1,2);
my $p = Geo::Point->longlat(2,1);
my $w = Geo::Proj->new(wgs84 => ...);
my $p = Geo::Point->latlong(1,2, 'wgs84');
my ($lat, $long) = $p->latlong;
my ($x, $y) = $p->xy;
my ($x, $y) = $p->in('utm31-wgs84');
my $p = Geo::Point->xy(1,2);