A few Machins that come from certain booklets have one or two straight sides (imperforate) rather than being cut down the center of the perforations. Many collectors "hate" stamps with a straight edge and refuse to collect them. However, it is these kind of stamps that prove very easily where they originated from.

There are eight possible positions available for imperforate sides. However, two of these positions have not yet been seen on Machin stamps.

Imperf Left & Top	Imperf Top	Imperf Top & Right
none	14p dark blue 19p flame 27p rust 29p purple 31p ultramarine 33p emerald green 39p amethyst 15p Anniversary 20p Anniversary 1st black 1st flame 2nd light blue 2nd dark blue	14p dark blue 19p flame 29p purple 15p Anniversary 20p Anniversary 1st black 2nd light blue
Imperf Left		Imperf Right
1p crimson 2p dark green 5p greyish rose 13p light brown 14p dark blue 17p dark blue 18p grey green 19p flame 20p black 24p rust 20p Anniversary		2p dark green 13p light brown 19p flame 20p black 20p flame 24p rust 20p Anniversary
Imperf Left & Bottom	Imperf Bottom	Imperf Bottom & Right
none	14p dark blue 19p flame 27p rust 29p purple 31p ultramarine 33p emerald green 39p amethyst 15p Anniversary 20p Anniversary 1st black 1st flame 2nd light blue 2nd dark blue	14p dark blue 19p flame 29p purple 15p Anniversary 20p Anniversary 1st black 2nd light blue