Okay, I'll refine the rule to "Treat any sequence of digits as a base 10 whole number for the purpose of sorting". I still think this is quite clear. (Frankly, I also think the original definition is quite clear unless you're purposefully trying to misinterpret it.)
> those names are strings having one or two characters. They are not "numbered files."
Yes they are! In this context, a number is an idea, not a data type. Strings are capable of containing numbers.