-the literal - (4510 / 558 / 2D16)
Group 1(START(?:(?:_[^_]*){4}-END).*?) STARTthe literal text START (case sensitive) Non-Capturing Group(?:(?:_[^_]*){4}-END) Non-Capturing Group(?:_[^_]*){4} {4}repeats the group contents below exactly 4 times:
_the literal _ (9510 / 1378 / 5F16)
Negated Character Class[^_]* *matches any number of characters outside the set below:
_the literal _ (9510 / 1378 / 5F16)
-ENDthe literal text -END (case sensitive) .*?any character (except for line terminators), repeated any number of times
_+the literal _ (9510 / 1378 / 5F16) , repeated at least once
\d+a digit, repeated at least once
Positive Lookahead(?=-END) -ENDthe literal text -END (case sensitive) 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