Longitude, as a decimal; positive values are east of Greenwich.
-=item sequence
-
-The ordinal position of this vertex, starting with zero.
-
=back
=head1 METHODS
|| $self->ut_number('zonenum')
|| $self->ut_coord('latitude')
|| $self->ut_coord('longitude')
- || $self->ut_number('sequence')
;
return $error if $error;