

Small barge photographs suggest an upright M, unlike the left-leaning appearance of the waving illustration. An advertisement showing the flag flat confirms an upright letter: its left diagonal and right leg are much thicker, about half a horizontal stripe’s width. The lower serifs match the illustration, but the upper ones point only outwards. The letter occupies about two-thirds of the flag’s height, larger than illustrated.
Bakker also observed the design as a pennant. Mertens notes that this form can coexist with a rectangular flag in inland shipping.