Options
            Regular expression options that let you specify how a regular expression pattern will be interpreted.
                
| Regular Expression | Description | 
|---|---|
| (?i) | Enables case-insensitive matching. For example, (?i)[A-Z] would match any upper-case or lower-case letter. | 
| (?m) | Enables multi-line mode. ^ and $ will match the beginning and end of a line, instead of the beginning and end of the text. | 
| (?n) | Enables capturing named groups only. (I.e., groups using this format: (?<name> subexpression).) | 
| (?s) | Enables single-line mode. ^ and $ will match the beginning and end of the text, instead of the beginning and end of a line. | 
| (?x) | Enables ignoring white space in the regular expression. | 
| (?-i) | Disables case-insensitive matching. For example, (?!)[A-Z](?-i)[A-Z] would match any upper-case or lower-case letter that was followed by an upper-case letter. | 
| (?-m) | Disables multi-line mode. ^ and $ will match at the beginning and end of the text, | 
| (?-n) | Disables capturing named groups only. | 
| (?-s) | Disables single-line mode. | 
| (?-x) | Disables ignoring white space in the regular expression. |