Question 1 Does a sans-serif typeface that uses an open 4 as a sail number as shown on the picture comply with the rules?
Answer 1 Yes. The sail numbers shown in this picture satisfy all the requirements of rule G1.2(a):
they are written using Arabic numerals,
all the numbers are of the same colour,
the colour used has a strong contrast to the body of the sail,
the typeface is sans-serif, and
the numbers are clearly legible when the sail is set.
It should be noted that not all variations of an open 4 will satisfy the last requirement and that legibility shall be assessed case-by-case. For example, numbers or letters created using a typeface resembling a digital 8 display or obtained as a cut-out of a squared number 8 will not comply with it: although they are clearly legible when considered one by one, when they are applied to both sides of a sail they may create confusion, therefore they do not comply with rule G1.2(a).
