In serial numbers etc., there are many cases where you can't tell if the intended character is a number or a letter. For example, the number
0 and the letter
O, the number
1 and the letters
I, and so on.
Is there a name for this concept/problem?
Background: I'm writing a spell corrector for my search engine that handles this situation. I'd like to know what this concept is called so I can document it properly.