This allows you to add arbitrary filled rectangles to the output page. A likely application would be to print barcodes. You can set fill-colour and edge-weight in advance:

© Simple black rectangle
 nlvml.Colour 0
 nlvml.Nib 0
 nlvml.PolyBar 20 20 100 100

You may pass a simple vector (the length should be a multiple of 4) or an (n,4) matrix of (xyxy) co-ordinates here giving the lower left and upper right of each bar. All co-ordinate values are in points, with the origin at the lower left-hand corner of the paper.

See also ...
nlvml.GRestore – restore co-ordinate system
nlvml.GSave – save co-ordinate system