? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
+ matches the character + with index 4310 (2B16 or 538) literally (case sensitive)
- matches the character - with index 4510 (2D16 or 558) literally (case sensitive)
This hyphen is treated literally, which might be confusing for others. Consider escaping it or placing at the start or end of the class!