P is an N-by-2 matrix in millimetres, one point per row; zero rows append nothing. A point marks a location without drawing anything through it — a setting-out mark, a hole centre, the origin a coordinate table is measured from.

It reaches a DXF file as a POINT entity, which is also how one arrives from a file: without it a drawing read back would lose every point it was given.

Source Code: draw.Drawing