The author makes a point of avoiding letters that are hard to distinguish even when spelled out in handwriting, but the example table includes the number 7. I can not count the number of times I have found it hard to distinguish between someone's 7 and 1.
It helps if you draw a horizontal bar on the 7 but many don't, so you can never really be sure if a 7 is in fact a 1 with the serif or vice versa.
It helps if you draw a horizontal bar on the 7 but many don't, so you can never really be sure if a 7 is in fact a 1 with the serif or vice versa.