AddSection

Call this method to add the actual coordinates in SegList:

Syntax: AddSection(Index: integer; var SegList: TFloatPointArrayEx)

For polyline datasets, the index parameter has no effect and you can just set it to 0.

For region / polygon objects it is important to store information about outer / inner rings (holes) correctly and different file formats has different requirements:

GML, KML, MITAB

Direction of coordinates: No requirements

Should be stored as first 1 outer and then N inner polygons.

This can be followed by further outer/inner sequences.

Index should be 0, 1, 2, 3 .... Change sign, if it is an outer polygon.

SHP

Direction of coordinates for outer polygons: Clockwise.

Direction of coordinates for inner polygons: Anti-clockwise.

Order of polygons and index parameter doesn't matter.

MIF and Array

No requirements

Common set of rules for all file formats

Direction of coordinates for outer polygons: Clockwise.

Direction of coordinates for inner polygons: Anti-clockwise.

Should be stored as first 1 outer and then N inner polygons.

This can be followed by further outer/inner sequences.

Index should be 0, 1, 2, 3 .... Change sign, if it is an outer polygon.

First and last coordinate should be the same for polygons or an error is raised.