a-z a single character in the range between a (index 97) and z (index 122) (case insensitive)
A-Z a single character in the range between A (index 65) and Z (index 90) (case insensitive)
äöü matches a single character in the list äöü (case insensitive)
\s matches any whitespace character (equal to [\r\n\t\f\v \u00a0\u1680\u2000-\u200a\u2028\u2029\u202f\u205f\u3000\ufeff])
matches the character -
literally (case insensitive)
This hyphen is treated literally, which might be confusing for others. Consider escaping it or placing at the start or end of the class!