^start of line
Requirementthe literal text Requirement (case sensitive) \d+a Unicode decimal digit, repeated at least once
\s*a Unicode whitespace character, repeated any number of times
\na line-feed (newline) character (ASCII 10)
Group 1((?:(?!^Requirement\d|.*?\[Distributed]).*(?:\n|$))*) Non-Capturing Group(?:(?!^Requirement\d|.*?\[Distributed]).*(?:\n|$))* *repeats the group contents below any number of times:
Negative Lookahead(?!^Requirement\d|.*?\[Distributed]) 1st Alternative^Requirement\d ^start of line
Requirementthe literal text Requirement (case sensitive) \da Unicode decimal digit
2nd Alternative.*?\[Distributed] .*?any Unicode character (except for line terminators), repeated any number of times
\[the literal [ (9110 / 1338 / 5B16)
Distributed]the literal text Distributed] (case sensitive) .*any Unicode character (except for line terminators), repeated any number of times
Non-Capturing Group(?:\n|$) \na line-feed (newline) character (ASCII 10)
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