Changing confirmation code format or excluding easily mistaken characters

I am using the confirmation code to authenticate within an app. Users manually enter this code from their email. I know I can alter the length of the code, but I don’t see any way to alter its format. When clicking on a link the format doesn’t really matter, but the difference between:

EGR0151 and
EGRO15I is not always that easy to see.

It would be great to be able to set this to lower case plus numbers, or perhaps exclude some of the more ambiguous characters altogether.