Multiline

Specifies multiline mode. Changes the meaning of ^ and $ so that they match at the beginning and end, respectively, of any line, not just the beginning and end of the whole string.

ExplicitCapture

Specifies that the only valid captures are explicitly named or numbered groups of the form (?<name>…). This allows parentheses to act as noncapturing groups without the syntactic clumsiness of (?:…).

Singleline

Specifies single-line mode. Changes the meaning of the period character (.) so that it matches every character (instead of every character except \n).

IgnorePatternWhitespace

Specifies that unescaped white space is excluded from the pattern and enables comments following a number sign (#). (For a list of escaped white-space characters, see Character Escapes.) Note that white space is never eliminated from within a character class.