Thanks for the QOD, Tom.

I appreciate the heads-up that a deceptively simple condition (like "where myLetter between 'a' and 'Z'") could result in a surprise if one expects it to filter just the 26 English letters in upper or lower case. The answer of exactly how many it would include is, of course not nearly so important as the possibility that it's greater than 52 (or 62 in your original poser which starts with the numeric digits).