line_segment
Returns a segment cut out of a simple line geometry.
The start and end points of the segment are specified by distances along the line, measured from its start. With a 3D line geometry, distances are in plan; if the start or end of the segment is between two vertices with height values, the segment end-vertex is given an interpolated height.
Parameter 1 - any geometry.
Parameter 2 - distance along the line for the segment start point. A negative value indicates a distance from the line end instead of the start.
Parameter 3 - distance along the line for the segment end point. A negative value indicates a distance from the line end instead of the start.
Returns: the line segment geometry. Returns null if the distance parameters are out of range or if parameter 1 is not a simple line geometry.