Regex Tester & Validator

Matches any line containing exactly one character that is not a digit (0-9) and not one of the letters i, I, o, O, q, Q, s, S, x, X, z, or Z. The multiline flags make ^ and $ anchor to line boundaries, so each line must contain a single qualifying character. Useful for validating single-character codes while excluding visually ambiguous letters (I/1, O/0, S/5, Z/2), though note it also matches symbols/punctuation since only those specific letters and digits are excluded.