Search | ~'aeiou' ? |
If the character being matched is a vowel, the test will look ahead until a character other than a vowel is found. this will be tested against the succeeding element. In this instance it will match if it is a letter, since ? matches any single letter.
If the character being tested is not a vowel, then the qualified element, in this case ~'aeiou' is itself ignored. So any character other than a vowel will be found.