All Regular Expression token sequence can be used with exception of a few tokens that are described in Errata here.
To test and capture Regular Expression token sequences, we recommend to use online tools such as “regular expressions 101” https://regex101.com/
You can simply test and copy/paste the token sequence from the tool and paste in the plugin parameter section.
Please read when handling SPACE by itself.
String Manipulation plugin is almost 100% compatible to standard Regular Expression. Only exception is handling of "space". When handling space alone as a single character, you must use double quotations around space i.e. " ".
When space is part of the string you try to find, no need to have double quotation. Examples are , (comma and space), a b (a space b), and a + (a space plus).
Finding space can be also done other tokens such as \s.