(?xim)applies the following effective flags to the remainder of the pattern: gmxi x modifier: extended. Ignores unescaped whitespace and comments outside character classes
i modifier: insensitive. Matches without distinguishing uppercase and lowercase letters
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string
^start of line
\s*a Unicode whitespace character, repeated any number of times
\d+a Unicode decimal digit, repeated at least once
\s+a Unicode whitespace character, repeated at least once
.*?any Unicode character (except for line terminators), repeated any number of times
\s+a Unicode whitespace character, repeated at least once
.*?any Unicode character (except for line terminators), repeated any number of times
\s+a Unicode whitespace character, repeated at least once
Group ExtList(?<ExtList>.*?) .*?any Unicode character (except for line terminators), repeated any number of times
\s{2,}a Unicode whitespace character, repeated at least 2 times
.*any Unicode character (except for line terminators), repeated any number of times
$end of line
Comment: //
Comment: (?<ExtList>.*)
Comment: \s{2,}
Comment: (?<BytesOr>(\|.{2}))*?
Comment: $
g modifier: global. Finds all matches instead of stopping after the first
m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string