What Letter and Number Mixups Need to be Considered?

Question

I just had a user tell me his registration key didn't work. It took me quite a while to figure out that he entered the capital letter "O" instead of the number "0".

So I decided that it is best for my registry checker to treat both "O" and "0" as equivalent, so both will work.

I can think of two other possible mixups:

1. The number "1" and the capital letter "I" and the small letter "l"
2. The number "5" and the letter "S" or "s".

Are these all of them, or are there others?

Answer 1

A better solution might be to display the registration key using a font that clearly differentiates between O and 0 and I, 1, and l. Alternatively you could rework the registration system so that the user, in the normal case, does not have to directly enter a key.

Answer 2

2 and Z or z. Possibly 9 and g, or 8 and B or 6 and G.