• ST_Curve type

• ST_LineString constructor

• ST_LineStringAggr method for type ST_LineString
• ST_NumPoints method for type ST_LineString
• ST_PointN method for type ST_LineString
• All methods of ST_Curve type can also be called on a ST_LineString type.
• All methods of ST_Geometry type can also be called on a ST_LineString type.

The ST_LineString type is a subtype of ST_Curve that uses straight line segments between control points. Each consecutive pair of points is joined with a straight line segment.

A line is an ST_LineString value with exactly two points. A linear ring is an ST_LineString value which is closed and simple.